How to add color background:

To add a color background, first click on design mode. Next, click the background tab and choose a zone. Then, hover over the zone and click the pencil icon. After, click the background color icon.

Here is how to add color background:

Step 1: Click the design tab. 

Step 2: Click Background tab (A). 

Step 3: Choose a zone (B). 

Step 4: Hover over the zone and click the pencil icon (same as editing a widget)

Step 5: Click the background color icon (C).