In order to play with your friends, all you need to do is join a match, find the game ID (it's the string of numbers that you can see on the newspaper front page) and send that over to your friend.

If you've received one of these game IDs, simply head to the Games tab, then to New Games, and you can search for the ID there. This will cause the game you're looking for to appear, and once you join it, you'll be playing with your friends.

Please keep in mind, however, that you must be using the same language version of the game as your friend, or the game will not appear.

I hope this helps - and good luck!