Need help with Painting Weights
 

I am trying to paint weights for a character that I have to animate. I've never done character animation before, and I have no clue what I'm doing. Everytime I paint the weights the character's skin gets deformed and I don't know how to fix it. It also doesn't seem like painting the weights is doing anything. For example, It looks like I fixed the weights on the legs, yet the legs still pull out other parts of the geometry when I move them. What's going on? What am I doing wrong, and how can I fix this? I need serious help!