Yet another clean little tweak.
Here’s the key to look for:
Change the “Background” key from the default blue RGB value (“0 78 152“) to let’s say “0 0 0” for a black background.
To set an image as the background, you want the key:
Set the value of “Wallpaper” to the path of the image file you want set as your background.
There are some other settings under the “Control Panel” tree worth taking a look at, have fun.