Help me change the Message to Screen GUI please?

I need to change the message to a Screen GUI.

timer = 10 -- Change this to the amount of seconds waited before a new map is chosen    
prefix = "" -- Whatever is in here will come before any messages appeared on screen

if Workspace:findFirstChild("MapsHere") ~= nil then
    print("Already in")
else
    mo = Instance.new("Model", Workspace)
    mo.Name = "MapsHere"
    print("MapsHere has been inserted")
end

while wait(5) do
    txt = prefix .. ": Preparing to insert a new map!"
    m = Instance.new("Message", Workspace)
    for i = 1, string.len(txt), 1 do
        m.Text = string.sub(txt,1,i-1) .. "" .. string.sub(txt,i,i)
        wait()
    end
    wait(2)
    m:Remove()
    maps = game.Lighting.Maps:GetChildren()
    num = math.random(1, #maps)
    for i = 1, #maps do
        if maps[i].Name == maps[num].Name then
            newmap = maps[i]:Clone()
            newmap.Parent = Workspace.MapsHere
            ntxt = prefix .. ": The map " .. newmap.Name .. " has been randomly chosen!"
            m2 = Instance.new("Message")
            m2.Parent = Workspace
            for i = 1, string.len(ntxt),1 do
                m2.Text = string.sub(ntxt,1,i-1) .. "" .. string.sub(ntxt,i,i)
                wait()
            wait(2)
            m2:Remove()
        while true do 
teleportHere = Vector3.new(-601.52, 750.27, -73.18) 

wait(22) 
local p = game.Players:getChildren() 
for i=1, #p do 
p[i].Character.Torso.CFrame = CFrame.new(teleportHere.x, teleportHere.y + ((1-i)*5), teleportHere.z) 

        end
    end
    wait(timer)
    getmaps = Workspace.MapsHere:GetChildren()
    for i = 1, #getmaps do
        getmaps[i]:Remove()
    end
    m3 = Instance.new("Message")
    m3.Parent = Workspace
    endtxt = prefix .. ": The current map has been removed, a new map will be picked shortly!"
    for i = 1, string.len(endtxt), 1 do
        m3.Text = string.sub(endtxt,1,i-1) .. "" .. string.sub(endtxt,i,i)
        wait()
    end
    wait(2)
    m3:Remove()
end