Step 1: Click on the billing link.

Step 2: Enter the email address of the person responsible for billing. This may or may not be your email. The portal will send an email with a link to log in. Check your spam if you don’t see it.

Step 3: Check your inbox for the email and click the link to log in.

Step 4: Click on "add payment method" to add a new credit card. You can also delete an old credit card by clicking the "X" next to it.