Creating login page with multiple users and destinations

Hi I'm kind of a begginer at this.

I need to create a log in page with multiple users and destinations. Not sure if its possible

my code:

<?php
// *** Validate request to login to this site.
if (!isset($_SESSION)) {
  session_start();
}
 
$loginFormAction = $_SERVER['PHP_SELF'];
if (isset($_GET['accesscheck'])) {
  $_SESSION['PrevUrl'] = $_GET['accesscheck'];
}
 
if (isset($_POST['username'])) {
  $loginUsername=$_POST['username'];
  $password=$_POST['password'];
  $MM_fldUserAuthorization = "";
  $MM_redirectLoginSuccess = "cieaeduc.php";
  $MM_redirectLoginFailed = "index.php";
  $MM_redirecttoReferrer = false;
  mysql_select_db($database_alterus, $alterus);
  
  $LoginRS__query=sprintf("SELECT cieaeducation, educators FROM clients WHERE cieaeducation=%s AND educators=%s",
    GetSQLValueString($loginUsername, "int"), GetSQLValueString($password, "text")); 
   
  $LoginRS = mysql_query($LoginRS__query, $alterus) or die(mysql_error());
  $loginFoundUser = mysql_num_rows($LoginRS);
  if ($loginFoundUser) {
     $loginStrGroup = "";
    
    if (PHP_VERSION >= 5.1) {session_regenerate_id(true);} else {session_regenerate_id();}
    //declare two session variables and assign them
    $_SESSION['MM_Username'] = $loginUsername;
    $_SESSION['MM_UserGroup'] = $loginStrGroup;          
 
    if (isset($_SESSION['PrevUrl']) && false) {
      $MM_redirectLoginSuccess = $_SESSION['PrevUrl'];    
    }
    header("Location: " . $MM_redirectLoginSuccess );
  }
  else {
    header("Location: ". $MM_redirectLoginFailed );
  }
}
?>