paragraph background color

I want to have the option of changing the background color of certain paragraphs so it looks a little darker from surrounding paragraphs. Right now all the paragraphs are the same color and not differentiated in any way. I have looked all over wordpress and there are always different paragraph or block background colors for code explanations, but not for normal paragraphs. My site is https://www.layofflist.org/.
Any help is appreciated.