How can i convert this client sided script into server side?

Hi so i have this local script inside of a GUI. I'm trying to make an among us style game, but the kill gui does not work properly. When the imposter kills, it only happens on the imposter screen also known as client sided. I don't have much experience with making stuff server side, as I usually build and make UIs. If you can provide how you would do it, thank you.

local gui = script.Parent
local players = game:GetService("Players")
local player = players.LocalPlayer
local run = game:GetService("RunService")
local sound = script.KillSound


gui.KillButton.MouseButton1Click:Connect(function()
local character = player.Character
if not character then return end
local head = character:FindFirstChild("Head")
if not head then return end
for _, v in pairs(workspace:GetChildren()) do
	if v:IsA("Model") and v:FindFirstChild("Humanoid") and v:FindFirstChild("Head") and v ~= character then
		
		if (character.Head.Position - v.Head.Position).Magnitude <= 20 and v.Humanoid.Health > 0 and script.Parent.KillButton.Timer.Visible == false then
			sound:Play()
			v.Humanoid.Health = 0
			character:MoveTo(v.HumanoidRootPart.Position)
			script.Parent.KillButton.Timer.Visible = true
			script.Parent.KillButton.Timer.Text = "10"
			wait(1)
			script.Parent.KillButton.Timer.Text = "9"
			wait(1)
			script.Parent.KillButton.Timer.Text = "8"
			wait(1)
			script.Parent.KillButton.Timer.Text = "7"
			wait(1)
			script.Parent.KillButton.Timer.Text = "6"
			wait(1)
			script.Parent.KillButton.Timer.Text = "5"
			wait(1)
			script.Parent.KillButton.Timer.Text = "4"
			wait(1)
			script.Parent.KillButton.Timer.Text = "3"
			wait(1)
			script.Parent.KillButton.Timer.Text = "2"
			wait(1)
			script.Parent.KillButton.Timer.Text = "1"
			wait(1)
			script.Parent.KillButton.Timer.Visible = false
			break
		end
	end
end
end)

run.Heartbeat:Connect(function()
local character = player.Character
if not character then return end
local head = character:FindFirstChild("Head")
if not head then return end
local cankill = false
for _, v in pairs(workspace:GetChildren()) do
	if v:IsA("Model") and v:FindFirstChild("Humanoid") and v:FindFirstChild("Head") and v ~= character then
		
		if (character.Head.Position - v.Head.Position).Magnitude <= 20 and v.Humanoid.Health > 0 and script.Parent.KillButton.Timer.Visible == false then cankill = true end
		end
	end
	if cankill then
		gui.KillButton.ImageTransparency = 0
	else
		gui.KillButton.ImageTransparency = 0.65
	end
	end)

What I would do is, wait for the button to be pressed from the Impostor, use a RemoteEvent to tell the server who their target is, check if the target is close enough and then do the kill. I would then fire to both clients (with a RemoteEvent), receiving the call with RemoteEvent.OnClientEvent and then I would display the Kill GUI and hide it after the appropriate amount of time.

you have posted the same question around 3 times, here is the answer again:

i remember the comment last time, so in a local script, your meant to use: game.Players.LocalPlayer to get the local player

LocalScript:

gui = Game.Players.LocalPlayer.PlayerGui["Name"] -- what went wrong
local players = game:GetService("Players")
local player = players.LocalPlayer
local run = game:GetService("RunService")


gui.KillButton.MouseButton1Click:Connect(function()
	gui.RemoteEvent:FireServer(player,gui) -- Carry over the player and gui variable
end)

run.Heartbeat:Connect(function()
	gui.RemoteEvent2:FireServer(player,gui) -- Different Remote ok?
end)

FIRE THE REMOTEFUNCTION

ServerScript:

local sound = script.KillSound


gui.RemoteEvent.OnServerEvent:Connect(function(player,gui)  -- Player variable used
	local character = player.Character
	if not character then return end
	local head = character:FindFirstChild("Head")
	if not head then return end
	for _, v in pairs(workspace:GetChildren()) do
		if v:IsA("Model") and v:FindFirstChild("Humanoid") and v:FindFirstChild("Head") and v ~= character then

			if (character.Head.Position - v.Head.Position).Magnitude <= 20 and      v.Humanoid.Health > 0 and script.Parent.KillButton.Timer.Visible == false then
				sound:Play()
				v.Humanoid.Health = 0
				character:MoveTo(v.HumanoidRootPart.Position)
				script.Parent.KillButton.Timer.Visible = true
				wait(1)
				script.Parent.KillButton.Timer.Text = "9"
				wait(1)
				script.Parent.KillButton.Timer.Text = "8"
				wait(1)
				script.Parent.KillButton.Timer.Text = "7"
				wait(1)
				script.Parent.KillButton.Timer.Text = "6"
				wait(1)
				script.Parent.KillButton.Timer.Text = "5"
				wait(1)
				script.Parent.KillButton.Timer.Text = "4"
				wait(1)
				script.Parent.KillButton.Timer.Text = "3"
				wait(1)
				script.Parent.KillButton.Timer.Text = "2"
				wait(1)
				script.Parent.KillButton.Timer.Text = "1"
				wait(1)
				script.Parent.KillButton.Timer.Visible = false
				break
			end
		end
	end
end)

gui.RemoteEvent2.OnServerEvent:Connect(function(player,gui)
	local character = player.Character
	if not character then return end
	local head = character:FindFirstChild("Head")
	if not head then return end
	local cankill = false
	for _, v in pairs(workspace:GetChildren()) do
		if v:IsA("Model") and v:FindFirstChild("Humanoid") and          v:FindFirstChild("Head") and    v ~= character then

			if (character.Head.Position - v.Head.Position).Magnitude <= 20 and v.Humanoid.Health > 0 and script.Parent.KillButton.Timer.Visible == false then cankill = true end
		end
	end
	if cankill then
		gui.KillButton.ImageTransparency = 0
	else
		gui.KillButton.ImageTransparency = 0.65
	end
end)

This is why remote events are the best thing, unless you can enable FilteringEnabled for easier but unsafe scripting