Open the + Tab to Add Friends. To see people nearby, tap 'Add Nearby or Bumped Into' to see who is and has been nearby to you. Add friends by name or username, from your Address Book, or by sharing your username. At the bottom of the tab, you will also find Quick Add to add people in the room.
Check the Friends Tab to see your Contacts. At the top, search for anyone on LOOK by their name, username, or number.
To add friends, tap the + button at the top right of the Friends Tab. In the search bar, search for anyone on LOOK by their name, username, or number. Below, see everyone in the room with you on LOOK. Tap the + button by their name to quick add them. You can also add contacts from your Address Book.