Some of our themes come with the ability to change the background image and color, by using the native WordPres functionality.
This applies mostly to themes with a boxed layout. In these cases, the background image will affect the area outside of the box container, so you may customize it freely.
You can change the background image by going to Appearance > Customize > General Theme options > Background Image. Here, you can upload an image to serve as your background. In some cases, that option will not be exactly in the same spot, but it is still in the Customizer. For example, for the theme Panoramica, the background image can be changed from Appearance > Customize > Background Image.
The background’s color can also be changed from the Customizer by going to Appearance > Customize > Colors > Background color.