How can I add friends from Facebook?
If you have already connected your Facebook account to the game, then your Facebook friends will automatically show up in your Friends List (as long as they also have connected their Tennis Clash account to Facebook).
How can I add friends from my Match History?
Just open your History and click on the name of a player you have been paired before, then tap on " Add Friend". A Friend Request is going to be sent to that player, who can Accept or Deny it.
Keep in mind it is only possible to add friends from your match history, and it is not possible to add players from the Global Ranking, for example.
How can I Invite a friend?
You can also tap on the " Invite" button in the Friends List screen to create a shareable link.
When your friends click the link it will open the game with a friend request (if the person who clicked the link does not have the game installed then it will take them to the download page).