I am trying to make a Gui show up on click, but the script just WON'T work!
script.Parent.MouseButton1Down:connect(function() script.Parent.Select.Visible = true end)
Is the thing you are trying to make "Visible" a Frame?
If it is a ScreenGui
then replace Visible
with Enabled
if it is a Frame that I don't have a clue. Also include the error message next time ;)