Background images

Any way to add a background images yet leave the main theme area white?
I’ve used a “Simple Full Screen Background Image” plugin on a number of websites and this one does make the background image appear but its through the main part of the website too. So you can’t view the text etc because the background image is there. Would be nice to allow a background image to only appear of the left and right sides or if there is margins set on the top and bottom.