You can update the credit card information on file by going to the Billing Page for your account. Below is a direct link to the Billing Page:
To find the billing information scroll all the way down to the Invoices section of the billing page. Right above the Invoices section is a link to “Show payment methods”.
If you click the “Show payment methods link you will see a button labeled “Change” which will allow you to enter new credit card details.