You need to adjust the CSS settings. contentarea, for example, has a margin-top of 67px and a margin-bottom of 60px. Just setting those to 0px would close up a lot of the spacing. footer_widgets also has a margin-top of 75px, which can be reduced to tighten up the footer.
I don’t know if your theme allows you to add custom CSS rules, but you can use a CSS plugin like Lazyest Stylesheet or Custom CSS Manager. You should learn how to use Firebug so you can examine the CSS rules for the elements you are interested in.