Instructions
Power on your PlayStation 3 and television. Select the "PlayStation Network" option from your PlayStation 3's home screen, then select the "Sign-in" option. Press the "X" button on your game pad to make your selections.
Enter the email address associated with your PlayStation Network account into the ID field, using the onscreen keyboard that appears. Enter your account's password as well, then select the "Sign-in" option.
Select the game you'd like to back up, then select the "Trophy" option. Press the triangle button on your game pad to sync your trophy information to the PlayStation Network.