Changing the background image for all articles

Hello. I am trying to change the background image for all of my articles without any success. I do not want the white background.
I am using the jp-sport template.
Any help that you can provide would be greatly appreciated.

Hello
the backgrounds of the sections can be changed in the customizer



All other things must be done in css/custom.css
www.joomlaplates.com/template-customizing

Yes, the customizer will change the color of the backgrounds for the sections but does not control selecting images for the background.

These settings also do not control the backgrounds of articles, only sections.

If I need to change the backgrounds of articles using CSS, then I will require examples of code to assist me.

1.) Images must be setup in theme settings background
2.) Background of content can be changed in customizer too
See image