How to Change Body Background?

Go to the ‘Appearance > Customize’ page from the admin panel menu.
Open the ‘Background Image’ tab.
You can upload a background image from the ‘Background Image’ field.
You will see position, size, repeat settings after upload an image.
Return the customize panel.
Open the ‘Colors’ tab.
You can change the background color of the body from the ‘Background Color’ field.