login

[onlinenova]

then i'm on my website i want to insert a sql code to say that there is a useronline but i don't no how / or where to put it?

<?php
//Login and Set Level
//Start Session Support
session_start(); 
?>
<?php require_once('Connections/siteconn.php'); ?>
<?php
mysql_select_db($database_siteconn, $siteconn);
$query_stats = "SELECT * FROM login";
$stats = mysql_query($query_stats, $siteconn) or die(mysql_error());
$row_stats = mysql_fetch_assoc($stats);
$totalRows_stats = mysql_num_rows($stats);

mysql_select_db($database_siteconn, $siteconn);
$query_online = "SELECT * FROM useronline";
$online = mysql_query($query_online, $siteconn) or die(mysql_error());
$row_online = mysql_fetch_assoc($online);
$totalRows_online = mysql_num_rows($online);

//Login & Set Level
$myUsername_rsLogin = "0";
if (isset($HTTP_POST_VARS['username'])) {
  $myUsername_rsLogin = (get_magic_quotes_gpc()) ? $HTTP_POST_VARS['username'] : addslashes($HTTP_POST_VARS['username']);
}
$myPassword_rsLogin = "0";
if (isset($HTTP_POST_VARS['password'])) {
  $myPassword_rsLogin = (get_magic_quotes_gpc()) ? $HTTP_POST_VARS['password'] : addslashes($HTTP_POST_VARS['password']);
}
mysql_select_db($database_siteconn, $siteconn);
// Verify Login is correct
$query_rsLogin = sprintf("SELECT username, password, userlvl FROM login WHERE username= '%s' AND password = '%s'", $myUsername_rsLogin,$myPassword_rsLogin);
$rsLogin = mysql_query($query_rsLogin, $siteconn) or die(mysql_error());
$row_rsLogin = mysql_fetch_assoc($rsLogin);
$totalRows_rsLogin = mysql_num_rows($rsLogin);

//Login and Set Level - Main
if($HTTP_POST_VARS['action']=="login"){
	if($totalRows_rsLogin==0){
		$errorMessage = "error";
		mysql_free_result($rsLogin);
	} else {

	mysql_free_result($rsLogin);
	session_register("user");
	$HTTP_SESSION_VARS['user'] = $HTTP_POST_VARS['username'];
	session_register("1");
	$HTTP_SESSION_VARS['1'] = $row_rsLogin['userlvl'];
	header("Location: game.php");
}
}
?>

where would i put it