1. Launch the Steam client software and log into your Steam account.
2. Click the Games Menu.
3. Choose Activate a Product on Steam...
4. Follow the onscreen instructions to complete the process.
Please see the Retail CD Keys article on Steam for a list of games accepted for registration on Steam.
Ensure that you are activating your game through the Steam application. 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: http://store.steampowered.com/about/
