So, I'm having a bit of trouble with the website that I'm making for my web design class. I've tried figuring out the problem on my own, but couldn't understand what was wrong. I asked my teacher, but he wasn't very clear or helpful (my teacher is not very good…ಠ_ಠ). So I don't think this could be considered cheating.

Here's the problem: the right side of the wrapper is extended to far at the top of the main area, and then cut off in the bottom-right corner. I don't understand what is happening, since all the width's within the wrapper are equivalent to 900px.
I assume there is a problem with the probably inconsistent sum of the heights (and amount of content), but any help would be greatly appreciated. i've included a zip of the website.
(trust me. the navbar lines up at school, but not at my home computer. also, the banner is partially blacked out for privacy reasons.