Fix page margins?

Hello,

I would like to fix my site’s bottom margins to make them not so close to the footer as it is now. You can view it at http://www.thedollbazaar.com and look at the farthest bottom, the footer (green) is very close to the “Wigs” category, I would like some space/padding there to separate them a little.
Also, there is the issue of the footer being inconsistent. For example, when there isn’t a lot of things on the page, the footer rises up, and the more items on the page it is farther down. Does that make sense? Example: Because of the widgets on the right on page “Accessories”, the footer is farther at the bottom, compared to page “Contact” where there is just the contact form and the so the whole page is “shorter”. I would like for it to be consistent without compromising the homepage.

How can I do this? I’m a beginner with web design so please be as detailed as possible, I appreciate everyone’s help here very much!! 🙂