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:

1. Launch the Steam client software and log into your Steam account.
   
2. Click the Games menu option at the top of the Steam client.
   
3. Choose Activate a Product on Steam...
   
4. Follow the onscreen instructions to complete the process.
   

Please see the Retail CD Keys article for more info on registering keys.

Register through browser

You can also register a CD key through a browser here.