when they click submit on the first page, it passes all the variables to the second page. There you have the following
foreach($_POST as $key => $value) {
echo "<input type=\"hidden\" name=\"" . $key . "\" value=\"" . $value . "\">\n";
}
Then on page 2, you have them click the enroll button (or whatever you want to call it), which submits the hidden form inputs to the credit card vendor via the POST method.
Or you can always register a session, but this is way is easy enough to do.
Cgraz