how do i change the gui of minigame script?

i'm using the basic free minigame selector script by zigza19 but i want to change the gui on it, but there isn't a gui in the startergui or in the script so is there even a way to change how the gui looks in the script?

this is the full script (its huge and pretty outdated even if it still works) im not sure if i change something in the script? i have not edited any of the basic stuff yet like name

--Original Scripts created by zigza19--
while true do --This makes sure it keeps going and doesn't die out on us
wait(5) --This is how long until the games are started. Recomended that you keep to 5
local m = math.random(1,1) --This randomly selects a game. The seven shows how many games there are
local player = game.Players:GetPlayers()
for i = 1, #player do --This checks for players and gets them
msg = Instance.new("Message") --This make the annoying messages that appear on you screen
msg.Parent = nil --This identifies the game
if m == 1 then --don't change unless you know what you are doing
msg.Parent = game.Workspace --This makes sure it says and appears in the workspace
msg.Text = "Choosing Minigame." --A bunch of messages to tell you that the game is starting which you can change if desired
wait(1)
msg.Text = "Choosing Minigame.."
wait(1)
msg.Text = "Choosing Minigame..."
wait(1)
msg.Text = "A Minigame has been chosen!"
wait(3)
msg.Text = "The Minigame is..."
wait(3)
msg.Text = "NAME HERE" --Put the name of the minigame you want it to be called
wait(2)
msg.Text = "INSTRUCTIONS HERE" --Put the rules of the minigame
wait(5)
msg.Text = "The game will be starting in:"
wait(1)
msg.Text = "...3..."
wait(1)
msg.Text = "..2.."
wait(1)
msg.Text = ".1."
wait(1)
msg.Text = "Begin!"
wait(1)
player[i].Character:MoveTo(Vector3.new(-60.54, 0.5, -67.337)) --Replace 206, 31.4, 48.5 with the location of where you want all players to be teleported to at the start of the minigame
msg:remove() --This removes the annoying messages Don't mess with!
game.Lighting.Minigame1:clone().Parent = game.Workspace -- Make a minigame then name it just like this: Minigame1 Once it is named that, put it in the position on the map were you want it to go then put the model in lighting. After you put the model in lighting, you may delete the one in workspace if you wish.
wait(60) --How long the game lasts
msg.Parent = game.Workspace
msg.Text = "Winner!" --After the game ends, this shows a message/messages at the end. Edit if you want.
wait(3)
msg:remove() 
game.Workspace.Minigame1:Remove() --Removes the brick so all players die (except spectators) and removes the brick so a new game can start (recommended games aren't over 5 minutes so spectators aren't bored)
end
if m == 2 then --New minigame You get the point. Remember these do not follow in order and are randomly selected!
msg.Parent = game.Workspace
msg.Text = "Choosing Minigame." --A bunch of messages to tell you that the game is starting which you can change if desired
wait(1)
msg.Text = "Choosing Minigame.."
wait(1)
msg.Text = "Choosing Minigame..."
wait(1)
msg.Text = "A Minigame has been chosen!"
wait(3)
msg.Text = "The Minigame is..."
wait(3)
msg.Text = "NAME HERE" --Put the name of the minigame you want it to be called
wait(2)
msg.Text = "INSTRUCTIONS HERE" --Put the rules of the minigame
wait(4)
msg.Text = "The game will be starting in:"
wait(1)
msg.Text = "...3..."
wait(1)
msg.Text = "..2.."
wait(1)
msg.Text = ".1."
wait(1)
msg.Text = "Begin!"
wait(1)
player[i].Character:MoveTo(Vector3.new(-143.5, 116.2, 163.5)) --Same old same old
msg:remove()
game.Lighting.Minigame2:clone().Parent = game.Workspace
game.Lighting.Knife:clone().Parent = player[i].Backpack --see the thing called knife? change the name of that is you want a weapon in the game for example a sword. Then put a weapon called Sword and YOU MUST PUT IT IN LIGHTING! if you cant drag it into lighting, right click on it then click cut then right click lighting then click paste into. MAKE SURE YOU PUT THE SWORD WHERE NO ONE CAN REACH IT!
wait(60)
msg.Parent = game.Workspace
msg.Text = "Winner(s)!"
wait(3)
msg:remove() --How long the game lasts
game.Workspace.Minigame2:Remove() --Ends the game
game.Lighting.Minigame2Points:clone() Parent = game.Workspace
wait(5)
game.Workspace.Minigame2Points:Remove()
end
if m == 3 then --If you want more just copy and past a minigame and set the number higher than the one before it and increase the number of games at the top
msg.Parent = game.Workspace
msg.Text = "Choosing Minigame." --A bunch of messages to tell you that the game is starting which you can change if desired
wait(1)
msg.Text = "Choosing Minigame.."
wait(1)
msg.Text = "Choosing Minigame..."
wait(1)
msg.Text = "A Minigame has been chosen!"
wait(3)
msg.Text = "The Minigame is..."
wait(3)
msg.Text = "NAME HERE" --Put the name of the minigame you want it to be called
wait(2)
msg.Text = "INSTRUCTIONS HERE" --Put the rules of the minigame
wait(4)
msg.Text = "The game will be starting in:"
wait(1)
msg.Text = "...3..."
wait(1)
msg.Text = "..2.."
wait(1)
msg.Text = ".1."
wait(1)
msg.Text = "Begin!"
wait(1)
player[i].Character:MoveTo(Vector3.new(234.5, 117.4, 141)) --this is the position the players will teleport to.
msg:remove()
game.Lighting.Minigame3:clone().Parent = game.Workspace
wait(10) 
game.Lighting.Sniper:clone().Parent = player[i].Backpack --weapon, lighting, you know what to do.
wait(60)
msg.Parent = game.Workspace
msg.Text = "Winner(s)!"
wait(3)
msg:remove() 
game.Workspace.Minigame3:Remove()
game.Lighting.Minigame3Points:clone() Parent = game.Workspace
wait(5)
game.Workspace.Minigame3Points:Remove()
end
if m == 4 then --Fourth game!
msg.Parent = game.Workspace
msg.Text = "Choosing Minigame." --A bunch of messages to tell you that the game is starting which you can change if desired
wait(1)
msg.Text = "Choosing Minigame.."
wait(1)
msg.Text = "Choosing Minigame..."
wait(1)
msg.Text = "A Minigame has been chosen!"
wait(3)
msg.Text = "The Minigame is..."
wait(3)
msg.Text = "NAME HERE" --Put the name of the minigame you want it to be called
wait(2)
msg.Text = "INSTRUCTIONS HERE" --Put the rules of the minigame
wait(4)
msg.Text = "The game will be starting in:"
wait(1)
msg.Text = "...3..."
wait(1)
msg.Text = "..2.."
wait(1)
msg.Text = ".1."
wait(1)
msg.Text = "Begin!"
wait(1)
player[i].Character:MoveTo(Vector3.new(-21.5, 48.2, 51.5))
msg:remove()
game.Lighting.Minigame4:clone().Parent = game.Workspace
game.Lighting.Sword:clone().Parent = player[i].Backpack
wait(60)
msg.Parent = game.Workspace
msg.Text = "Winner(s)"
wait(3)
msg:remove() 
game.Workspace.Minigame4:Remove()
end
if m == 5 then --Fifth game!
msg.Parent = game.Workspace
msg.Text = "Choosing Minigame." --A bunch of messages to tell you that the game is starting which you can change if desired
wait(1)
msg.Text = "Choosing Minigame.."
wait(1)
msg.Text = "Choosing Minigame..."
wait(1)
msg.Text = "A Minigame has been chosen!"
wait(3)
msg.Text = "The Minigame is..."
wait(3)
msg.Text = "NAME HERE" --Put the name of the minigame you want it to be called
wait(2)
msg.Text = "INSTRUCTIONS HERE" --Put the rules of the minigame
wait(4)
msg.Text = "The game will be starting in:"
wait(1)
msg.Text = "...3..."
wait(1)
msg.Text = "..2.."
wait(1)
msg.Text = ".1."
wait(1)
msg.Text = "Begin!"
wait(1)
player[i].Character:MoveTo(Vector3.new(-2.5, 51.4, 56.5))
msg:remove()
game.Lighting.Minigame5:clone().Parent = game.Workspace
game.Lighting.Sword:clone().Parent = player[i].Backpack
wait(60)
msg.Parent = game.Workspace
msg.Text = "Winner(s)!"
wait(3)
msg:remove() 
game.Workspace.Minigame5:Remove()
end --This end all the scripts so they can start over like a big happy cycle! DON'T MODIFY THEM AT ALL!!!
if m == 6 then
msg.Parent = game.Workspace
msg.Text = "Choosing Minigame." --A bunch of messages to tell you that the game is starting which you can change if desired
wait(1)
msg.Text = "Choosing Minigame.."
wait(1)
msg.Text = "Choosing Minigame..."
wait(1)
msg.Text = "A Minigame has been chosen!"
wait(3)
msg.Text = "The Minigame is..."
wait(3)
msg.Text = "NAME HERE" --Put the name of the minigame you want it to be called
wait(2)
msg.Text = "INSTRUCTIONS HERE" --Put the rules of the minigame
wait(4)
msg.Text = "The game will be starting in:"
wait(1)
msg.Text = "...3..."
wait(1)
msg.Text = "..2.."
wait(1)
msg.Text = ".1."
wait(1)
msg.Text = "Begin!"
wait(1)
player[i].Character:MoveTo(Vector3.new(12.2, 15.7, -0.5))
msg:remove()
game.Lighting.Minigame6:clone().Parent = game.Workspace
game.Lighting.Sword:clone().Parent = player[i].Backpack
wait(60)
msg.Parent = game.Workspace
msg.Text = "Winner(s)!"
wait(3)
msg:remove() 
game.Workspace.Minigame6:Remove()
end
if m == 7 then
msg.Parent = game.Workspace
msg.Text = "Choosing Minigame." --A bunch of messages to tell you that the game is starting which you can change if desired
wait(1)
msg.Text = "Choosing Minigame.."
wait(1)
msg.Text = "Choosing Minigame..."
wait(1)
msg.Text = "A Minigame has been chosen!"
wait(3)
msg.Text = "The Minigame is..."
wait(3)
msg.Text = "NAME HERE" --Put the name of the minigame you want it to be called
wait(2)
msg.Text = "INSTRUCTIONS HERE" --Put the rules of the minigame
wait(4)
msg.Text = "The game will be starting in:"
wait(1)
msg.Text = "...3..."
wait(1)
msg.Text = "..2.."
wait(1)
msg.Text = ".1."
wait(1)
msg.Text = "Begin!"
wait(1)
player[i].Character:MoveTo(Vector3.new(50, 116, 31.5))
msg:remove()
game.Lighting.Minigame7:clone().Parent = game.Workspace
game.Lighting.Sword:clone().Parent = player[i].Backpack
wait(60)
msg.Parent = game.Workspace
msg.Text = "Winner(s)!"
wait(3)
msg:remove()
game.Workspace.Minigame7:Remove()
end
end
end