A customer places an order for your Shopify store. You receive money via your payment gateway most likely, Shopify. The order goes from being "authorized" to "paid" which you'll be able to view in your Orders section. Once the order is paid any order that has a MXED related item within in will appear in the MXED orders page. To purchase the product click the "Order Product" button and enter in your credit card details.
Your profit is the difference between the cost of (product + shipping) and price you decide to charge your customers