如何强制下载列出和链接的文件,还打开404?

My problem is that I am wanting a personal file storage website to use between different computers, I have little PHP knowledge, yet more in HTML+CSS. I have found how to list files in a directory on a server, that appear to have a link to download. However, if you proceed to click on this list, it loads a 404 error page. Should it not download? How could I make it to force download the file? Also, all files should be able to be downloaded, not just a certain type (e.g .pdf or .jpg). I have looked extensively on this website and others, but haven't found a working solution.

     <body>
    <?php
     if ($handle = opendir('./uploads/')) {
       while (false !== ($file = readdir($handle))) {
              if ($file != "." && $file != "..") {
                $thelist .= '<li><a href="'.$file.'">'.$file.'</a></li>';
              }
           }
      closedir($handle);
      }
    ?>
    <h1>List of files:</h1>
    <ul><?php echo $thelist; ?></ul>
</body>

Thanks,

Much better solution is create FTP server. It is easier managing, faster dw/up