Things You'll Need
Instructions
Plug an Ethernet cable into its corresponding ports on the backs of both consoles you're connecting. It looks like an elongated phone jack port.
Power on both systems and insert "Modern Warfare 2" into the consoles. Choose the option to play the game from the system's launch menu.
Select the "Multiplayer" option on the right side of the game's title menu.
Select "System Link" from the list of options in the menu that follows. Allow the systems to establish a connection. A pregame lobby will then open to allow players to join a match.