please help with deveoping a context dfd

Develop a context diagram DFD of the acquisition/payment system at Oriental Trading. A purchase requisition is sent from the inventory system to Sky Ishibashi, a clerk in the purchasing department. Sky prepares a purchase order from information in the vendor and inventory files and mails it to the vendor. The vendor returns a vendor acknowledgment to Sky indicating receipt of the purchase order. Sky then sends a purchase order notification to Elei Mateaki, a clerk in the accounts payable department. When the receiving department accepts vendor goods, the inventory system notifies Elei by sending him a receiving report. Elei also receives invoices from the various vendors. He matches the invoices with the purchase order notification and the receiving report and updates the accounts payable master file. Elei then sends a payment authorization to the accounting department. There, Andeloo Nonu prepares and mails a check to the vendor. When the check is issued, the system automatically updates the accounts payable master file and the general ledger