Brands can add a credit card to their account at any time by clicking on their name in the top corner of the left menu then selecting My Account. Next, click Payment Methods listed under Brand in the left menu.
From here, you can view any credit cards that are already stored, change the default payment credit card, or add a new credit card by clicking the orange +Add Card button near the header bar.
You will then be prompted to add all information associated with the credit card including a nickname (it can be whatever you want). Finally, you can select if you want this card to be added as the default payment method (you can change this at any time).