This is the LAN version of the game. You can send the game to your friends to play. If you are playing in the same room, you dont need to type any IP adress.
Just press the button (Disable Match Making) then one player press the LAN Host button (He will be the host) and the others the LAN Client button to join.
Remember to disable the firewalls, and press disable match maker button to access to the LAN Host Button and the LAN Client button.
If you are not in the same place (Different houses for example), the one that does as host (Pressing LAN Host (H) Button) must give the IP Adress to the other players, and the other players must introduce the IP Adress in where its written (localhost) beside the LAN Client(C).