How to change the background post color

I would like to change my post background from white to black on all my pages. I have tried a lot of things but I don’t have a lot of experience in coding.My website is www.filthyrichent.com the section I’m talking about is under the news section.Also I also trying to get closer spacing in my store for the items.

Hi,

I just checking your site and looks like you are not using out themes