still can't get a login with session working ... is there another way to mask the url parameter?

["Terion Miller" <webdev.terion@xxxxxxxxx>]

Still this won't pass the session to the next page.... is there a way to
pass parameters in the url but mask them? maybe that would be easier, since
I do have code that works passing the adminID on the url ...
can a parameter be hashed after the fact?  I tried echo-ing the fields on
the next page and they are not passing...
my code that still doesn't work:

<?php
// start session
  session_start();
 include("inc/dbconn_open.php") ;
 $errs = error_reporting ('E_ALL');

if (isset($_POST['UserName'])) {$UserName = $_POST['UserName'];} else
{$UserName = '';}
if (isset($_POST['Password'])) {$Password = $_POST['Password'];} else
{$Password = '';}

$msg = '';

if (!empty($UserName)) {

    $sql = "SELECT * FROM  admin WHERE  UserName ='$UserName' and Password
='$Password' "
    or die(mysql_error());
    $result = mysql_query ($sql);
    $row = mysql_fetch_object ($result);
    If (mysql_num_rows($result) > 0) {
        $_SESSION['AdminLogin'] = $row['AdminID'];
        header ("Location: Main.php");
    } else {
        $msg = "Invalid Login";
    }
}

?>