Through the infra-red communication. It's the icon next to the Game Icon. Press that on both tamas, the screen will say 'Playmate?' Choose Ver.3 on both of them and then the thing you want them to do, either Visit, Present or Game. Choose for example Game on both of them and both screens will say 'Stand-by'. Now press the B-button on both tamas and it will say 'Connect' and shortly after they will play with each other.