Struggling with a theme

Making a website as part of a proof of concept. I’m really new to wordpress, tried to search around this and a few other forums but I’m at a loss so I figured I’d ask.

We finally managed to agree on a template, you can see it here: http://www.dessign.net/moderntheme/. I managed to get wordpress installed on the site without any problems but when I loaded up the theme there was a lot of negative space where there had been content placeholders on the demo site of the theme as you can see here http://gamingnews.xtreemhost.com

I can figure out how to add widgets and stuff to the sidebar on the right, but I can’t figure out how to add content to the larger margin left of it where the mockup content had been on the demo site. Just can’t figure out how to plug things into that space. Any help or pointing in the right direction is greatly appreciated.

JM