Header-image in Twenty?

Hi! Is there a possibility to set a image as header in Twenty-theme? In the Screenshot in the Skeletons there is one (woods) ...

Just look at how this is done in Antimatter and apply similar Twig + CSS to Twenty. So you see, anything is possible, just takes a little work.

Thanks for your response, hukster. I used to play a lot with Antimatter, I just thought, that (regarding the screenshot) there is a "direct" way to set a wallpaper, or, in other words: Where do these trees come from? ;-)

Trees

Ok, I found it by myself, it's the banner.jpg in /user/themes/twenty/images