Click on My Home Page.
in the search box, type the screename of the person you want to add. If they have a profile viewable to others, it will pop up (otherwise, you can't add them).
When the profile pops up, on the left hand side, it will have their screen name, a link to their fitness journal, and a button that says "Send friend request"
Starting Weight: 2/10/2014 353.9 lbs.