You can add a credit card to your payment profile by entering your information at the time of registration or purchase. Just click, Save my credit card.
To update information about your current saved credit card, like a new expiration date:
Log in to your Account from the website Login. Click Account.
Once there, click Payment Profile. Delete your saved credit card that needs updating. You will then be asked for payment information when you purchase or register for a program on the website. You can choose to Save My Credit Card, at that time.