Step 1: First, navigate to the "Design" section.

Step 2: Proceed to the "Appearance" section.

Step 3: Now find and click on the "colors" tab.

Step 4: Here, you will find the section for "background-color". This is where you can select and change the color.

Step 5: Once you have chosen your desired color, remember to press "save".

With these steps, you should now see that the background color of your store has effectively been changed.