Art help

Ok, I am taking Drawing I this sememster and had a few questions for those of you that can draw. How in the hell do you get the charcoal to wash off? I washed my hands like a million times lastnight and I can still see some under my fingernails. Also, I am having trouble with getting my body parts drawn equally in size. Like the legs look too small. Or one side of the face is fine and the other side is all wrong. Any pointers? Oh, and please keep in mind (if you didn't already know) that I CAN'T draw. Thanks.