icon or text activates script

I'm currently making an iPhone game. I have a pause script which lm trying to activate by clicking on an icon image or GUI text on the iPhone screen.

On the computer, the pause script would work by either hitting the ESC or Spacebar key, but since the iPhone doesn't have those keys, a visual display is needed to activate pause menu.

How would I link an icon image or GUI text to activate the pause menu. Which script would I use or is there a tutorial.

Thank you