How do I register a CD Key to activate a product on Steam?
Please follow these instructions to activate a new retail purchase on Steam:
Please see the Retail CD Keys article for more info on registering keys.
Ensure that you are activating your game through the Steam application. The Steam website cannot be used to activate a game. If you have not yet done so, you can download and install the Steam application by clicking on the green "Install Steam Now" button here: