Write some Software

I need someone to prepare IPN code that goes on to my website that responds to PayPal. Confirms the purchaser's order information from PayPal and allows communication to the buyer of a book to download it. PayPal is saying I have code on our website respond to and confirm purchase and insure a valid order and to allowing to information on how to download the PDF to the buyer from a dedicated page on our website via that page's URL or send a email with the book's PDF or the book attached. The price is $6.99. Let me know if you can help. Thanks!