This is more from a customer's perspective but it is important to understand what steps and process they go through for you to receive a client order from the user interface.
-Go to "Shop" from the UI menu.**
-Select a category and click the desired item to order.
-Set a quantity of the item.
-You will see the total items ordered on the right side of the client shop.
-Once done settling the orders, choose a payment method.
-Click "Submit Order" to continue or "Cancel order" if you need to make changes on your orders or cancel it.
-Once the order was confirmed, you will see this pop-up message notifying about your outstanding bill and when you should pay it. The message may vary depends on the payment method.
NOTE: **"Shop" button may be labelled differently depending on the client theme that you are using.