First, you'll need to create a Chase Pay account if you don't have one already. Then, log in and make sure all information in your account is up-to-date and your payment methods are linked. Fill your Vitacost cart with healthy goodies and click "Checkout." At checkout, select "Pay using Chase Pay"
This will open a pop up and prompt you to login using your chase.com username and password. Then select your desired payment method from your chase pay account and select next. This will bring you back to the Vitacost checkout page where you can complete the transaction.