From the main menu screen, press the "Deathmatch" button, and it should take you to the screen above.
Press the "Multi-Snailer" button and that enables the multiplayer menu directly to the right (all the buttons in that menu should change from grey to color)
In the little menu on the right, press the "Start" button to start a game and wait for someone to connect. If someone else already started a game, they will appear in that menu automatically, and you simply press "Connect" to connect to them.
This works much better if you talk to someone via messenger, and schedule a game to be played. I think a chat is going to be built into future versions, but don't quote me on that.
