I need help with a DFD,I only need it in level one.

SHOE ORDER SYSTEM A DFD Construction Exercise Narrative: A customer orders running shoes from a company, Road Runner, in San Diego, CA. There are two ways that she can order her shoes though the web or on the 800 telephone number. The following narrative illustrates the web process for ordering shoes: The system determines whether the customer is a current or new customer. If the customer is a new customer, the system must collect all the necessary information. If the customer is a current customer, verify credentials and check to see if there needs to be an update to their information. After verifying the customer information, the system determines whether or not the order can be filled. The system accesses the inventory database to determine whether the shoes are in stock or must generate a backorder notification. After determining the shoes are in stock, the system generates a shipment request and sends it to the Warehouse. A customer invoice is also created to be stored in Accounts Receivable and sent to customer. After receiving the shoes from the Warehouse, the shoe order is prepared for shipment to the customer. The customer invoice is sent from Accounts Receivable. In addition, the system must check to determine if the customer is a member of the Road Runner Club. If so, then deduct 10% on the customer invoice. Finally, ship the shoes and customer invoice to the customer. Instructions: Create a DFD that accounts for all aspects of the above narrative