how to debone a turkey breast

I'm assuming you are talking about a half breast in which case you only have to deal with the breast bone and ribs. It helps to have a sharp, flexible boning knife. All you will be doing is to begin at the small end and follow the bone toward the meatier end pulling away as you go. You could almost do this without a knife.

Here's a video tutorial:
http://www.youtube.com/watch?v=5WE4VHZzJPw