Well basically, I created my site to work on my computer monitor, and as they vary, [mine is 1024px] it messes up the site. http://clubpenguin-hd.com/ - It should show no background, and the header covering the whole of the top area. Apparently, in other screen sizes, everything but the header is okay. It looks messed up. How can I fix it?

I can set my monitor to various width, now it is 1920 and the site looks fine - it is a fixed width site and the area behind the site is blue stripes. What wrong with that?