Fonts! Please Help!!!

First off my blog is pretty simple… its http://celtics247.com/blog My two questions where, first where do you edit the fonts for your wordpress theme? Is it in the style.css folder? I want to change the font of the main font in the blog posts. Secondly, does anyone know the font that the K2 theme for wordpress uses? I like that font and would like to know what font it is exactly. Thanks for any help!