Select the Play option with the bullseye. Then select the Versus option.
You can play against the computer by selecting the Computer option. To play against another player on a network, select the Network option.
If your computer is connected to the internet, the Tracker will come up, which shows all internet-based games available.
To host a game, click on the Host Game button. Write a game description. Set a password if you want to play a private game with your friends. Select the game type, and then click on Host Game. If your computer is connected to the internet, your game will be listed in the Tracker.
If you are on a local area network, your game will not be listed on the Tracker, but will be waiting for another machine on the network to join you.
To join a game, click on Play, then Versus, then Network.
Again, if your computer is connected to the internet, this will bring up the Tracker. To join one of these games, simply click on the game in the Tracker list to select it, and then click on the Join Game button at the bottom of the screen.
To join a game hosted on a local area network click the Join Private button. If you have never played against this machine before, you will need the IP address of the hosting machine. If you have played on this network before, it will list the IP addresses that have hosted games previously. Enter the IP, or select one of those listed, and then click on Join Game and you are all set!
If you are on a computer running OS 9, you can play against another player on the same machine.