After logging into your Steam account on our account management website and selecting the service you want to pay for you will have the Steam payment option available to you.
Select it and click on the Next button to make a payment with your Steam Wallet. Before pressing the button please make sure that you have the required funds in your Steam Wallet. You will be taken to the Steam payment page to finalize the payment.
Also please make sure you are logged into your Steam client with the same account you wish to pay for, before logging into our account management pages to make your payment.