Blizzard (US)

Redeem Your Code on the Battle.net Website
To redeem a code on the website:
1.Log into your Account Overview
2.Enter the code in the Redeem a Code box and click Redeem Code

Redeem Your Code On The Battle.net Desktop App
To redeem a code on the Battle.net Desktop App:
1.Login to the Battle.net Desktop App
2.Click your profile icon at the top right corner of the App
3.Click Redeem Code

Redeem Your Code On The Battle.net Mobile App
To redeem a code on the Battle.net Mobile App:
1.Login to the Battle.net Mobile App
2.Click Profile
3.Expand the Account section
4.Choose Redeem Code