You can add a user to your friends by going to Menu > Friends and looking their Facebook name (if you're linked to a Facebook profile) or username up. Once you find them, tap on their information to access the user's profile and tap on "Follow". That way, you'll be able to play together, and they'll appear on your Friends list any time you enter this section again.
Bear in mind that you'll also be able to invite friends that are not currently on the game via link through the different social apps. To do so, follow these steps:
- Tap on the "Send link" button you'll find at the bottom left of your screen, next to your ongoing games.
- Once you do this, different social apps you can use to invite your friend to the game will be displayed.
- Once your friend receives and accepts the invitation, they will appear as a friend available to play every time you want to start a new game.
If you wish to invite a new friend, you'll have to follow these same steps again.