If you sit, a GUI pops up?

I know basic scripting, I just don't know all the basics. So, I can't get my script to work. The script basically should have a GUI pop up when you sit on it, and when you get off it should go away(I don't know how to do that).

script.Parent.ChildAdded:connect(function()
	game.Players.PlayerGUI.Gui.Frame.Visible = true
end)

Thanks.

This Way, If You Sit, It First Searchs For "SeatWeld", Which Is A Weld That Appears When You Sit. Then It'll Insert A Gui Into Your PlayerGui(PlayerGui is In Player Always. If You Have Something In StarterGui, It Automatically Goes To Player Gui.)

script.Parent.ChildAdded:connect(function(newChild)
	if newChild.Name == "SeatWeld" then
		local Gui = Instance.new("ScreenGui", game.Players:GetPlayerFromCharacter(newChild.Part1).PlayerGui)
	end
end)