OK guys I found this out about a hear ago.
OK On the first page. Your sales page, you put your paypal, or whatever button on. Below is an example

<form action="https://www.paypal.com/cgi-bin/webscr" method="post">
<input type="hidden" name="cmd" value="_xclick">
<input type="hidden" name="business" value="ronaldRFarmer@gmail.com">
<input type="hidden"...