How to activate a Steam Gift Card key?
Redeeming a Steam Gift Card is really easy, just follow these simply steps:
1/ Log into your Steam account or create a new account, and click the "Redeem a Steam Wallet Code" button.
2/ Enter the code that you received into the “Steam Wallet Code” field.
3/ Select Continue.
4/ Subsequently, the denomination value of the gift card will be added to your Steam Wallet. You can see your balance in the upper-right corner of your Steam account.
The key is not working
If you have activated the key according to the guide but the code appears not to work, please check what type of error message you receive and depending on it follow the appropriate instructions: