Blizzard Redeem Guide:
Step 1: Visit https://battle.net/code, create an account an account if you do not have one / login to your existing Blizzard account to redeem the game:
Step 2: You should be able to start download the game client after redeeming the game, if it does not show you the download page, please refer to link below to download and install your game.
Step 3: Download and install the Blizzard client and login with the Blizzard account that you’ve redeemed the game.
Step 4: Install and play the game.