Onclick Text

Hi everyone!

I am trying to build a page similar to this:http://www.bathjunkie.com/shop/build.../body-dessert/

So far I have most of it done. I just don't know where to begin when creating a function to:
onclick text --> text appears in empty input boxes.

This is how far I am with my code: http://jsfiddle.net/dcummin13/VrMXE/4/