CSS positioning help

I'm making a new website, which can be found here (no comments yet please, it's still under major construction). As you can see on the left, one half of the rectangle is slightly larger than the other. This is to emphasize my problem. The "Featured Site" box and the "Navigation box" should be on opposite sides of the site.

The stylesheet can be viewed at www.delta.arroways.com/stylesheet.css and any help is appreciated on how to get the divs where they are supposed to be.

PS. I tried using positioning, and it just isn't working, can anyone find my error?
PSS. The site is under major development, so the stylesheet's a mess, sorry.

Thanks!

EDIT: I fixed the problem, you can now look at www.delta.arroways.com/index2.php Thanks for reading this post anyway.

http://intensivstation.ch/files/templates/temp06.html this is a great resource to so check this out.

http://intensivstation.ch/templates/

eng: http://intensivstation.ch/en/templates/

Your stylesheet link should be http://www.delta.arroways.com/stylesheet.css

Oops, that was a mistake.