1. Go to: http://store.steampowered.com/ and download STEAM client.
2. Click "Install Steam" (from the upper right corner)
3. Install and start application, login with your Account name and Password (create one if you don't have).
 
4. Please follow these instructions to activate a new retail purchase on Steam:

    Launch Steam and log into your Steam account.
    Click the Games Menu.
    Choose Activate a Product on Steam...
    Follow the onscreen instructions to complete the process.


Here’s how you can play Legacy Evolve:

Right-click Evolve in Steam and select “Properties”
Go to the "Betas" tab
In the dropdown, select "legacyevolve - The Original Evolve Product"
Click "Close"
Wait for the game to download the differences
Enjoy Legacy Evolve