Want background color/image behind main menu

I would like to put a background image or color behind the main/primary menu area. The area above the slider.

If I could – I would like the menu background change/color/image to show inside the site only, not on the home page – the slider page. I love the home page as is.

I need to break up some white space. Away from the front page with the slider – my site looks a bit sterile. My site content is primarily text. Images are just to fill a visual void.

The header background image is a space waste for me – plus my users are on tablets and phones. There is too much scrolling thru nothingness to reach the content on each page. I am a terrible desinger, even with a great theme.

Any clue to pinpoint the code and parameters to edit the CSS file would be greatly appreciated. I am using a child theme.

toni-esl.com
Thank you

I have the issue with the slide order in the Customizer too, they will not move. But I can delete.