Hey, not sure if you've managed to figure it out yet or not, but I hope this answers your problem you're having. Before following the information below, check to see if your prepaid card may require a PIN configured. There is usually a website on the card somewhere for you to check this just to be sure:


1) While checking your Steam Wallet, there should be an option to "Add payment method to this account". Click/Tap that option, then fill out the necessary information in the fields provided.

2) For "Billing Address", despite it being a prepaid card, do put down your usual Billing Address as it is needed to send a "bill of sale".



Once that is all said and done, you should be good to go to spend whatever you've got on your cards.


Happy Gaming and hope this helps!