Background showing between floating elements

Hi- just trying to figure out why my background would be showing between elements on my home page and how I can eliminate that. I just want the background to show on the sides and possibly a tiny bit at the top of the page. It has to be an easy fix, but I’m stuck and don’t know what terms to use when searching the web.

Current test website:
https://www.PlumStreetPrints.com/wordpress

Thanks!