How to set a color overlay on a background image

Hello, sorry if this question is stupid.
So I just finished the Tea Cozy exercise, and I decided to play around with it a little more, styling random stuff. But I kind of got stuck on a very simple thing.
Let’s say I want a color overlay on the background image of my banner, or, conversely, I want to set an opacity for my background image so that it shows a color underneath, how do I do that in the cleanest way possible?
I’ve looked around but all the methods I found were a little trickier (nested divs or box-shadows, mostly) and even though they seem reasonable I was wondering if there is a proper way to do this, a simple clean solution.
Event though I usually find a way to ‘make it work’ I often fear I’m overcomplicating things and I don’t want to pick up bad habits, so any help on th is would be much appreciated!
Thanks in advance