Instructions
Purchase the game online or from a retailer. Make sure that the promotion code card comes with your purchase, as this is the only way to receive it.
Start the game and then click on the "Extras" option from the main menu by pressing the "X" button. Scroll down to the "Unlockables" option and press the "X" button.
Enter the number code that came with your game into the text box provides in the "Unlockables" screen. Enter the code as it appears on the promotional code card, and don't use any dashes or spaces.
Press the "X" button and you will then see a pop-up message indicating that your code was successful and that you've unlocked extra outfits.
Complete the second contract missions in the game to be able to use the outfits that you unlocked and then go to the "Extras" option from the main menu. Click on the "Outfits" option by pressing the "X" button and your new outfits will be available to use.