1) Tap on Customer in the side menu to enter the Customer dashboard.
2) Select the customer you want to add a card to.
3) Tap on Billing
4) Tap on Add a Card on the bottom of the screen.
5) Fill out the required information of the card and then tap Add Card.
6) To add the Customer to a plan, simply click Add Plan within the Billing section, and select from your Plans. You can also Create a New Plan.