Instructions
Turn on the PS3 and allow the main menu to load. Navigate to the "PlayStation Store" using the left analog stick, and press the "X" button to move to the "PlayStation Store" menu. Highlight the "Add On" option and press the "X" button.
Highlight the "Search by Title" option and press "X." Highlight "C" on the screen and press "X" to bring up a list of games starting with the letter "C." Search through all the game titles to find "Call of Duty Modern Warfare 2." This takes you to a menu of all the downloadable content for the game.
Search through the list of downloads by using the left analog stick. A brief description of each download will appear on the right of the screen. Use the right analog stick to scroll through the text. Press the "X" button to download the file.
Select the memory device you want to download the file and press "X." When you are prompted to confirm the download, press "X" and the download starts. Do not turn the system off or remove the memory device from the system during the download.