Where do you find a list of users so you can add someone as a friend to your homepage?: )
You can add your friends via Facebook under "Find more friends on Facebook"under the leaderboard or you can check out the discussions to discover members you'd like to follow. Just click on the person's photo and click 'add friend'.
Or, if you know the Duo's nickname of a friend, just search it in the "Search learners" engine on the top right of all Duo's pages.