How to have less margin/padding within footer?

Hi all, How do I remove some of the padding (white space) above and below the images in my footer on this page? I'm presuming it has something to do with adding a #site-generator reference in my Custom CSS. But, I'm not quite sure how to specify it. BTW: Is there a document which discusses the default "sections" of the wordpress theme? It'd be helpful, rather than having to always ask since they're not always intuitive. Thanks! Robert