Instructions
Turn on your PS3.
Select "PlayStation Network" from the menu.
Open the "PlayStation Store" icon.
Select the "Games" category listing, followed by "Search." Type "Resistance: Fall of Man" into the "Search" box. All of the downloadable content for "Resistance" will appear on screen, including the map packs.
Select the "Add to Cart" option next to the map pack you want to download. As of May 2011 the "Resistance: Fall of Man" map packs cost $4.99. Select "Proceed to Checkout" and "Confirm Purchase" to buy and download the map pack you have selected.
Press the "PS" button on your controller. Highlight "Quit" and select the option with "X" to exit the PlayStation Store and return to the menu.
Select "Game." Select the icon for the "Resistance: Fall of Man" map pack you've downloaded. This will install the map pack onto your copy of the game. The maps are now available to use in the game.