You must sign up for a Free Membership before you can purchase credits. If you have not yet signed up, click here to learn how. To purchase credits, login and click on "My Account" located in the navigation bar at the top of your home page. In your account page, click on "Purchase Credits" located in the right-hand column. Upon completing the required fields and clicking the "Purchase" button, your billing information will be verified. The credits will then be distributed to your account.