no puse el username ni el password aqui por seguridad

Código PHP:
$host="localhost"; // Host name
$username=""; // Mysql username
$password=""; // Mysql password
$db_name="fenixto_es_db"; // Database name
$tbl_name="usuarios"; // Table name
// Connect to server and select databse.
$link = mysql_connect("$host","$username","$password");
mysql_select_db("$tbl_name",$link);
// username and password sent from form
$myusername=$_POST['username'];
$mypassword=$_POST['password'];
// To protect MySQL injection (more detail about MySQL injection)
$myusername = stripslashes($myusername);
$mypassword = stripslashes($mypassword);
$myusername = mysql_real_escape_string($myusername);
$mypassword = mysql_real_escape_string($mypassword);
$sql="SELECT * FROM $tbl_name WHERE username='$myusername' and password='$mypassword'";
$result = mysql_query("SELECT password FROM usuarios WHERE nick='$nickN'");
// Mysql_num_row is counting table row
$count=mysql_num_rows($result);
// If result matched $myusername and $mypassword, table row must be 1 row
if($count==1){
// Register $myusername, $mypassword and redirect to file "login_success.php" , no me deja ponerlo por motivo de spam"
session_register("$myusername");
session_register("$mypassword");
header("location:login_success.php");
}
else {
echo "FALLASTES";
}
en login_success.php hay va un link solo q no me lo deja poner aqui.