Instructions
Insert your "Guitar Hero: World Tour" game disc into your console. If the PlayStation 3 doesn't automatically load the game's menu, select the icon for the game in the "Game" category of the menu.
Select the category listing for multiplayer from the "Guitar Hero: World Tour" main menu.
Select the type of multiplayer game you'd like to play. You can choose between online competitive games or online cooperative games.
Press the "PS" button on your controller. The PlayStation 3 main menu will display over top of the "Guitar Hero: World Tour" game on your console.
Highlight the "Friends" category. Highlight the user name of the friend you want to invite to your game. Press the "Select" button on the PS3 controller to send an invitation for that friend to join your game. Press "PS" on the controller again to return to "Guitar Hero: World Tour." Wait for that friend to accept your request and join your game.