How to get a CD Key for free
1 - First step is to register as the member
2 - Go to the "Earn Coins" page
3 - Choose an offer and complete it with valid information
4 - After completion your coins will be automatically awarded to your account and you can get the Half-Life 2: Episode One CD Key
About This Game
Half-Life 2 has sold over 4 million copies worldwide, and earned over 35 Game of the Year Awards. Episode One is the first in a series of games that reveal the aftermath of Half-Life 2 and launch a journey beyond City 17. Also features two multiplayer games. Half-Life 2 not required.
Source: Half-Life 2: Episode One - SteamPowered.com
Instructions to activate steam keys
1 - Download and install the Steam client on your PC.
2 - Open the Steam client, login and locate the Games tab on the top menu. Click this and then select “Activate a Product on Steam…”
3 - Enter your product key that appears on the email and follow the instructions to activate it.
4 - Your game is now viewable in the “Library” tab and is available to download/install when you’re ready