Help!

Okay, I need some help here. I have an old picture of Chris' parents (Keith and Diane), an engagement picture, I think. Keith wrote a sweet love note to Diane on the back of it. What I'd like to do is superimpose the writing onto the picture. My problem is that I want in Keith's handwriting. I've scanned both sides of the photo, I just don't where to go from here. If anyone has any ideas or websites that can do this, PLEASE let me know.