Hello, it seems that :
3. Custom BackgroundSparkling theme supports WordPress Custom Backgrounds feature.
In WordPress dashboard go to Appearance -> Background.
You can either set the image or solid color as background.
You can see the background preview on the same setting page.
Click Save Changes when you are satisfied with what you see.
You can always reset theme default background.
does not work as there is not such an option in wordpress or at least on my installation.
So how to change the background color of the site or put an image instead?
Thanks!