How to retrieve your Steam account details:
Open the Steam client or visit Steam Store;
Sign in to the Steam account where you want the funds applied;
Confirm you are on the correct account (wallet is account-specific);
How to redeem:
Purchase the Steam voucher and locate the wallet code in your order confirmation or email;
Open the Steam client on PC or go to Redeem a Steam Gift Card or Wallet Code;
Click Games in the top menu, then select Redeem a Steam Wallet Code;
Enter the wallet code exactly as shown;
Confirm redemption;
The funds will be added to your Steam Wallet immediately.