Instructions
Turn on the PS3 console and log into your user account. The PS3 home screen will appear.
Select the "PlayStation Network" icon on the home screen, select "Account Management" and then press the "X" button.
Select "Facebook" from the "Account Management" screen and press the "X" button. A prompt will appear.
Input your Facebook log in email address into the top box and your Facebook password into the bottom box. Select "Confirm" and press the "X" button to link your Facebook account to your PS3 user account. Now, newly earned trophies will be announced on your Facebook wall.