How can I make a menu that spans across multiple different GUIs?

Here's what my Explorer looks like:

http://i.imgur.com/nQCiWsq.png

When a TextButton is pressed, I want it to remove the current ImageLabel being displayed (Main) and show a different ImageLabel. The only problem is I have no idea where to start. Any help? <3

Maybe something like this?

function TextButton1()
	TextButton1.Transparency = 0
	TextButton2.Transparency = 1
end

function TextButton2()
	TextButton1.Transparency = 1
	TextButton2.Transparency = 0
end

script.Parent.TextButton1.MouseButton1Click:connect(TextButton1)
script.Parent.TextButton2.MouseButton1Click:connect(TextButton2)