Steam Wallet codes work just like gift cards which can be redeemed on your account for Steam Wallet credit and used for the purchase of games, software and any other item you can purchase on Steam. You can find Steam Wallet Codes at many retail stores across the World in a variety of denominations and different currencies.
Go to steampowered.com/wallet and sign in if you aren't already. You will need to create a Steam account if you do not already have one.
Geographic restrictions apply. Review the Terms for details.