Once you are in the Library (https://tisch.academy) you'll see all of the course videos listed down the welcome page.
In the upper right corner click on your avatar.
A menu will drop down with the options My Library, Settings, and Log Out.
Select "Settings" On your setting page look in the top right corner for the words "Billing Info" Click on that link.
That will take you to your billing information page where you will see your credit card information.
Click on the "..." to the right of your current credit card. An option will drop down saying "Update Card" click that to change your credit card information.