how do I add a picture on my photo? and can I use a computer wall paper or something? and how do I add/accept friend requests'
If you click on "My Page", you should see a link to upload your photo. (In the past, I've had to try several times to get this to work -- not sure why.)
At the very top of the page, there are three small tabs. The last one, with a little symbol of a person on it, is the friends page. You can accept friend requests there.