Open search and type the username. Send a friend request. If that request costs tokens, a confirm step shows the cost. The other person accepts for free, or declines.
You can cancel a request that is still waiting. The friends list can be searched. Unfriend hides the chat for you and removes vault shares between you.
Groups and the website
Open an invite link to join a group. Links expire. You cannot add someone you blocked, or someone a member has blocked.
On the website, Find someone starts a text chat. Pick a city page when you want people looking in that city. That chat is not added to your friend list unless you claim an account and add them.