Orders in a status of "Deposit Required" or "Balance Due" must be paid before they can move forward. When viewing the order, you should see a green "Make Payment" button on the top-right of your order (see below):
In this example there is an Amount Due of $319.20
Click the "Pay Now" button to initiate the payment process. The next page allows you to enter your preferred credit card information:
Click "Submit Request" to process payment.
The Status of the order now moves into "In Production":
The payment is also posted to the messages tab so everyone is aware: