As for editing your profile, find a picture you like and then upload it to your profile albums which you can see here:
Once you do that, go to your profile and hit the 'customize profile' button which you can see here:
Once you click that button this should pop up:
Once it does, look in the box labeled 'Main' and you should see something that
says 'Background Image' with an empty white box and a polaroid picture next to it.
To upload your background image, you are going to need to click that polaroid picture.
If you are not sure where to find it here is where it's located:
Once you click it, a list of your albums should pop up on the right. Click the album you uploaded the image you wished to use as your background image to, and then click the image and the link will appear in the empty white box next to the words 'Background Image'
Then hit the save button, which you can find here:
(You can also preview the background before you save it and the preview
button is to the left of the save button.
By clicking the 'Customize Profile' button, not only can you change your background image, but you can change the colors, fonts, ect. of your profile as well.
For more information about how to edit your profile (and how to do the things listed above), click HERE