help with a simple script

Hi, not sure what you want, because you haven't said much.
But from what I understand you should create html form, where user will choose some options. form attribute action will be
action="<?php echc $_SERVER; ?>" which means that form will be submitted to the same page. Action attribute will be post - action="post". Then you can chceck at the beginning of the file if user submitted values you expect. For example:

<?php
//check if form with your desired value has been submitted
if (isset($_POST['numpages'])) {
    //check if there is data you want
    //some people can use telnet to post unwanted data
    if (preg_match('^/[\d]{1,2}/$',$_POST['numpages']) {
        $numpages = $_POST['numpages'];
    } else {
        Header("Location: ".$_SERVER['PHP_SELF']);
        exit;
    }
}
?>

(I haven't tested this code, it's just ilustration),
then you check if all values ($numpages, ...) are set, if yes
then you submit it to paypal.
If you want to use paypal express checkout, download my code from here:
http://sourceforge.net/project/showfiles.php?group_id=246036

hopefuly it helps
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