Joining friends in-game

[Doubletime]

Under <Game Name>.

That's assuming he is the host though, since the game would appear as (Your Friends Name here)'s Game.

If he isn't the host, ask your friend for the host of the games name.

If there is no host, you or your friend should host one.

The only thing to keep in mind is that if your friend's game is full -- meaning it has 5 players already in-game -- that game will not appear in the join game list because it is not an eligible game. Only games with less than 5 players appear in the join game screen. So it is always best to message a friend first to see if there is a spot available before trying to join.