How to color behind the black lines in adobe photoshop elements 9?

I have adobe photoshop elements 9 and I want to color in a hand drawn picture on my computer but in all the tutorials I've watched they have always colored behind the lines of the actual picture. I can't figure out how to do this on my version of photoshop so if anyone knows how to, please tell me. It would be a big help and I would really appreciate it. Thanks in advance.

I use GIMP, but Photoshop has the same features. Put a new layer over the hand-drawn picture and set it to multiply. Color on that layer and it should go over the original hand-drawn layer while remaining behind the black lines.