Prepopulating a webform

I would like to capture a few user data on a webform on my site and then when the user clicks submit, it prepopulates my ClickBank order form with the same data. How is this acheived?

 

PHP form handling would be your best bet. There are several tutorials, here is one that helped me back when I started learning PHP: http://www.webdesign.org/web/web-programming/php/form-handling.11101.html

Hope that helps.