You can easily review, add and/or update your saved credit card/s associated with your account.
1. Sign in with your email and password.
2. Go to My Account
3. Then go to Settings
4. Select Credit Cards
5. Edit, Remove or Add Credit Cards to be saved on your account.
Learn what to do if you need help Updating your Password.
If you need help with how to Review your Account Balance please check out this article.