Key activation instructions:
1. Download (http://steampowered.com/download/SteamInstall.msi) or launch the Steam client.
2. Log in or register a new account on steam.
3. In the lower left corner, click on "+ Add game", and then click on "Activate on Steam" and enter the activation key for the game, which you will receive after payment.
After that, the game will appear in the "Library" section.