Auto-reply to clients that purchase through PayPal

The task is to write a simple API for PayPal and combine it with my website. When a client makes a purchase through my website and pays with PayPal s/he should receive an automate e-mail with a 'thank you' message and a link to download purchased products. The automate response should be personalized with clients name and surname. I use [login to view URL] for building my website therefore I do not have full access to the domain and files on the website. As far as I know I have access to HTML (not PHP), if this helps, and am able to upload files to it although I am not sure if the website can be adjusted to trigger any file if required. This is where your skills are required. To combine website created and managed in [login to view URL] to PayPal API to make auto responses. At present I have PayPal premier account but I am happy to upgrade to a business account if required, as long as this is not PayPal Website Payment Pro option. I am not interested in a middle man like paydotcom etc to do the auto reply for you. Note: this is different than auto redirecting option at PayPal that redirects a client to a website after a completed purchase. For someone who understands API this should be very easy therefore I suggest 10-12 pounds project value. Feel free to contact me if you have any questions or require additional information. Thanks.