well, if the computers are on the same network, u just go to multiplayer, and scroll down to lan/local play, there someone should create a game and it will appear for everyone else. if u are not on the same network (like a big network with many sub networks) u will have to type the ip adress but it will still work (for example when me and my friends play on different computer labs of our university). if ur computers are not in a network at all, u should use hamachi. hope it helps...
