Style Sheets are HARD

I've been working forever to try to figure out how to pull the body of these posts up next to the floated menu, but it won't start until below it for some reason. The only exception is when I manually float the post part of my style sheet to float left, but then if a post doesn't span the entire main body, another will butt up next to it, so I'll have two posts horizontally on one line. WEIRD! If any random people see this post, know something about style sheets, and know what I might be able to do to fix it, please let me know! Otherwise, I'll just keep trial and error crap with it.