help!

As those of you who've stopped by here before can tell, something went terribly wrong with the layout of this blog. I wanted to change things up a little, and made a new banner, except I've no idea how I made it all soooo wide and off center...:(( I'm embarrassed to admit how long I spent trying to figure out how to fix this, but I'd LOVE it if anyone could give me a direction/ help me center everything again.

Thanks a million!