If you found another user that you like, the two of you should become friends.
To send a friend request to another user, click on their Captain to see their Profile pop-up:
Then just click on the green button in the bottom right corner:
Once the friend request has been accepted, the other user will appear in your activity bar. You will now be notified each time a friend writes you a message, levels up, creates a Look or starts playing “Dress Up”.