Painting application

Now I am looking forward in the next tasks I have to deal with Scoilnet and one seem to me too hard to finsih, a painting tool for kids.

On a section of the site, I want to let kids click on a black and white image, and by choosing some colors, fill the drawing with nice colors, and print their result.

I can surely doing that with flash, but Flash is not allowed in this project. So I read quite a lot on GDI+ in VB.Net, but so far I saw only things fro drawing lines, squares or other objects.

Do you have some ideas on this subject ?

After my last search, I think Regions is probably a way to look, but how can I test pixels to say something like 'stop to fill here, this is the end of this region' ?

And good other question:
Do you know some good links about GDI+ with deeper content, not only the basic stuff ?