Instructions
Turn on the Xbox 360 and insert the "GRAW 2" disc.
Select the Marketplace from the Xbox 360 main menu.
Choose "Games."
Select "GRAW 2."
Select one of two map packs: "Throwback Pack" or "Throwback Pack 2." Both packs are free.
Allow the map packs to download. They will become installed on the game and available once you turn "GRAW 2" on.