Instructions
Select the "Back" option on your game console controller. This will exit the "Call of Duty: Modern Warfare 2" offline multiplayer screen and return you to the general multiplayer menu of the game.
Select "PlayStation Network" if you are playing the game on a PlayStation 3. This will load the online multiplayer options for the game, switching your account from "offline" to "online" mode.
Select "Xbox LIVE" if you are playing the game on an Xbox 360. This will load the online multiplayer options for the game, switching your account from "offline" to "online" mode.
Select "Find Lobby" to begin playing a game of "Call of Duty: Modern Warfare 2" online.