There are two types of backgrounds, one for your profile and the other for the site.
i. Log in to your account and go to your profile
ii. Click on the "Design My Page" tab at the top of your profile.
iii. Scroll down to ”Profile Background” and choose a color; or
iv. You can also add an image to your background by uploading an image to the site or profile background image box.
v. When you are done, click "Save" at the bottom of the page.
vi. Wait for your new design to be approved by the moderator!