Turtle return

So I've ran into a problem. How would a computer to react to a message that was sent to it. For example if the computer received certain text it does a certain function.

Depends a bit on whether that "computer" is doing anything else at the same time.

But in simple terms, you have that computer open a rednet side, then wait to receive messages sent by another system. Apply a loop if you want to deal with consecutive messages.

Well its hopefully going to be putting the information on a screen which tells me if the turtle is returning or at home

Also could someone help me understand this button API?
like how to create buttons?

http://pastebin.com/pFHeia96