I Want Header, Content & Sidebar Background To Be Different from Page Background

Right now, my website looks like a Tumblr-type blog would (the header, main menu, content body and sidebar are all separated). I would like to have all of these things on one solid white background IN FRONT of the current background I have. Essentially, I am looking to have a layout like HipHopDX.com or KevinNottingham.com where there’s a background, but it’s behind the content’s background. Please help! I googled everything I could and cannot find an answer!