Well you need to setup your lan interface, of course, which involves compiling a driver for your lan interface into the kernel and configuring your hostname, IP adress, subnet mask etc.
Once you did that and can actually communicate with other machines in your lan (eg ping, transfer files), you can play any game using this connection. Assuming the game has a multiplayer option of course.
Typically playing a game over lan uses the following scheme:
One host (eg with the IP 192.168.0.1) starts the game in a server mode. It will then wait and listen for other machines. Other hosts in the same lan (eg 192.168.0.5, 192.168.0.144,...) can connect to this server as clients. Then they can all play happily together or frag the heck out of each other.
That was a general overview as I didn't quite understand what problem it is that you are having with that game.