Change the color of the website "behind" the web copy?

I hope I am explaining this correctly, but I know how to change the background colors and whatnot, but what I would like to do is make the copy area of a page post and widget remain white, but I would like to make the area behind those a light shade of grey so that there is some separation between the various items.

Is there any way to do this with catch evolution pro?

Thanks!