For each section you have the ability to set either a background colour or background image.
Below provides an example of what both look like when assigned on a website
BACKGROUND COLOUR
Multiple colours cannot be selected for one page panel, only one solid colour.
BACKGROUND IMAGE
When adding a background image, this should be a solid image.
Maximum upload file size: 50 MB. 1600 x 800 pixels is recommended. Make sure the image is cropped to suit the parts of the image you wish to have displayed.