Redeploying with an arsenal of content unlike any in franchise history, Call of Duty®: Modern Warfare® 3’s first downloadable “Collection” arrives stockpiled with not only four Multiplayer/Survival Mode Maps, but two Special Ops Missions—the first time Call of Duty® has ever made Special Ops downloadable online. Armed with just this one content pack, players can choose between heading to a militarized Central Park in Liberation, destroying scenic vistas in a seaside Italian getaway in Piazza, raining glass on New York passersby from 70-stories-up in Overwatch, and battling beside a downed Air Force One in Black Box. As if that breadth of multiplayer variety wasn’t enough, fans of Special Ops can hop aboard snowmobiles to infiltrate a diamond mine in Black Ice or head to India, where Negotiator will leave the fate of hostages in their hands. In a class of its own with half-a-dozen forms of content, Modern Warfare® 3’s first downloadable “Collection” offers a range of combat and co-op the likes of which has never been seen before.

Go to: http://store.steampowered.com/ and download STEAM client Click "Install Steam" (from the upper right corner) Install and start application, login with your Account name and Password (create one if you don't have). Please follow these instructions to activate a new retail purchase on Steam: Launch Steam and log into your Steam account. Click the Games Menu. Choose Activate a Product on Steam... Follow the onscreen instructions to complete the process. After successful code verification go to the "MY GAMES" tab and start downloading.