Coupon Code for Small Website

Hello, I have a client who sells a very small amount of items on his web page through paypal, "add the cart" buttons. We use the paypal cart and not our own. I built the web page and know basic xhtml, css, javascript. My client wants to be able to give some of his customers "coupon codes" which can be entered on the website (in a text input box near the paypal buttons) giving them a special discount and then sending them to the paypal cart to check out. He wants to be able to creat as many coupon codes as he wants, but for now only about 5. I have done research on how to do this myself and it seems slightly out of my reach, but I understand the workflow. Please get back to me ASAP as this is a time sensitive project. ## Deliverables This is a time sensitive project. Please respond ASAP