sessions, register user

Hej! Jeg har hentet et login script og er igang med at modificere det lidt.
Som det er nu er der et "Sign in" link på forsiden der bringer en til register.php. Er man logget ind i forvejen kan man ikke oprette en ny bruger hvilket virker logisk nok.
Problemet er at det skal være sådan at kun en admin skal kunne oprette brugere. Så er spørgsmålet, hvordan ændre jeg dette?

Flg. er min register.php:

<?
if($session->logged_in){
  echo "<h1>Registered</h1>";
  echo "<p>We're sorry <b>$session->username</b>, but you've already registered. "
      ."<a href=\"main.php\">Main</a>.</p>";
}
/**
* The user has submitted the registration form and the
* results have been processed.
*/
else if(isset($_SESSION['regsuccess'])){
  /* Registration was successful */
  if($_SESSION['regsuccess']){
      echo "<h1>Registered!</h1>";
      echo "<p>Thank you <b>".$_SESSION['reguname']."</b>, your information has been added to the database, "
          ."you may now <a href=\"main.php\">log in</a>.</p>";
  }
  /* Registration failed */
  else{
      echo "<h1>Registration Failed</h1>";
      echo "<p>We're sorry, but an error has occurred and your registration for the username <b>".$_SESSION['reguname']."</b>, "
          ."could not be completed.<br>Please try again at a later time.</p>";
  }
  unset($_SESSION['regsuccess']);
  unset($_SESSION['reguname']);
}
/**
* The user has not filled out the registration form yet.
* Below is the page with the sign-up form, the names
* of the input fields are important and should not
* be changed.
*/
else{
?>


<?
if($form->num_errors > 0){
  echo "<td><font size=\"2\" color=\"#ff0000\">".$form->num_errors." error(s) found</font></td>";
}
?>
<form action="process.php" method="POST">
<table align="left" border="0" cellspacing="0" cellpadding="3">
<tr><td>Username:</td><td><input class="input" type="text" name="user" maxlength="30" value="<? echo $form->value("user"); ?>"></td><td><? echo $form->error("user"); ?></td></tr>
<tr><td>Password:</td><td><input class="input" type="password" name="pass" maxlength="30" value="<? echo $form->value("pass"); ?>"></td><td><? echo $form->error("pass"); ?></td></tr>
<tr><td>Email:</td><td><input class="input" type="text" name="email" maxlength="50" value="<? echo $form->value("email"); ?>"></td><td><? echo $form->error("email"); ?></td></tr>
<tr><td></td><td>
<input type="hidden" name="subjoin" value="1">
<input class="submitlink" type="submit" value="Join!"></td></tr>
<tr><td colspan="2" align="left"><a href="main.php">Back to Main</a></td></tr>
</table>
</form>

<?
}
?>

</body>
</html>
**************************************************************

Min process.php ser således ud (dog kun register-delen):

  function procRegister(){
      global $session, $form;
      /* Convert username to all lowercase (by option) */
      if(ALL_LOWERCASE){
        $_POST['user'] = strtolower($_POST['user']);
      }
      /* Registration attempt */
      $retval = $session->register($_POST['user'], $_POST['pass'], $_POST['email']);
     
      /* Registration Successful */
      if($retval == 0){
        $_SESSION['reguname'] = $_POST['user'];
        $_SESSION['regsuccess'] = true;
        header("Location: ".$session->referrer);
      }
      /* Error found with form */
      else if($retval == 1){
        $_SESSION['value_array'] = $_POST;
        $_SESSION['error_array'] = $form->getErrorArray();
        header("Location: ".$session->referrer);
      }
      /* Registration attempt failed */
      else if($retval == 2){
        $_SESSION['reguname'] = $_POST['user'];
        $_SESSION['regsuccess'] = false;
        header("Location: ".$session->referrer);
      }
  }


******************************************************************

Jeg glæder mig til at høre jeres forslag.