How to change the banner from the admin panel?

[Kishyong]

My template fetches the banner from the CSS file with the code: `height: 30em; background-image: url(images/banner.jpg); background-position: center; background-size: cover;`. I also want to change the path of `banner.jpg` from the admin panel. I copied the CSS code to index.php and tried changing `background-image: url();` but it didn't work. How can I achieve this?