Confused about CCD image processing?

I know I often am. Many times I seem to drive my images into the ground. I passed a site that has a demonstration of some image processing that is well laid out and helped me clarify my understanding of HOW TO DO IT. Aside from the numerous good books etc, this site apppealed to my simple side.

http://www.mv.com/ipusers/astron/CCD_image_processing.htm