This is in no way my turf but all I can say is that paint.NET is a free image and photo editing software for computers that run windows. It works with layers and can be used to do all sorts of stuff like Drawing, Creating logos, adding special effects to pics, resizing, and lots more. I also used it to add watermarks to my pictures.
You can read more about it here
http://www.getpaint.net/index.html
I'm pretty sure someone else who can give a more in-depth answer to your question will come along.