How Can I add him to my friends?

I'm italian and if I mistake in writing, excuse me, please.
If I add a friend on this forum, I have got that person betwixt my friend on the game?
If this isn't that, I have another request...
I've got a friend that he play the game on his smartphone but he isn't on facebook... Please, how can I add him to my friend and play again him or sent packages?

The forum is separate from the game.

I do not know how to add a friend that plays on the phone.

I hope someone else who reads this does, it is a good question.

On the first question, like Cat Harrison said, the forum is separate from the game and for the second one, you can't add him on friends if he is playing directly from the phone.