Editing a theme

Hi i just installed the gallery theme on my site http://www.epicdesktop.com. Its going to be a wallpaper site but its the first wallpaper site I’ve made using wordpress (got some using wallpaperscript).

The problem Ive got is as you can see, the wallpapers sit on the right hand side of the site with a big gap on the left (left gap was sidebar.php with a search box). That is a static page called “latest”.

Does anyone know how I can get rid of the gap? There is no gap when I set the main page to be latest posts but I dont want to have to upload 3,000 wallpapers into seperate posts.

thanks