如何访问根目录之外的文件并使用它们

Question

First of all I ask for an apologize, I know this question had been asked and already been answered but I still can not figure out what to do.

I put my files outside and before of root directory and want to access it when a customer purchases a file. I know I can use this method for downloading but I want this to get the file and let me to send it into other page and there customer click on the link to download it and also mention that a customer may have purchased many files.

How can do the same for all files? Should I put them in a loop?

Here is my code:

<?php
$file = 'monkey.gif';
if (file_exists($file)) 
{
    header('Content-Description: File Transfer');
    header('Content-Type: application/octet-stream');
    header('Content-Disposition: attachment;    
    filename='.basename($file));
    header('Content-Transfer-Encoding: binary');
    header('Expires: 0');
    header('Cache-Control: must-revalidate, post-check=0, pre-  check=0');
    header('Pragma: public');
    header('Content-Length: ' . filesize($file));
    ob_clean();
    flush();
    readfile($file);
    exit;
}
?>

Thanks in advance.