Instructions
Select "Multiplayer" from the main menu, then sign into the PlayStation Network using your email address and password.
Click "Create A Class" and select a class for the character whose gun you want to camouflage.
Select the gun you want to use, then click "Camo." Scroll down the list of available camouflage and select "Green Tiger."
Press the "Square" button on your PlayStation 3 controller to go back to the Multiplayer menu -- your changes will be automatically saved.