กำหนดขนาดหน้าต่างยังไงครับ เรื่อง Cookie ด้วยครับ 1.ผมจะทำเครื่องคิดเลขใส่ในเว็บครับ แล้วตอนนี้ผม

<?
	session_start();

	$Username = trim($_POST["txtUsername"]);
	$Password = trim($_POST["txtPassword"]);
	
	//*** Check Username ***//
	if(trim($Username) == "")
	{
		echo "<center><font color=red>** Plase input [Username]</font></center>";
		exit();
	}
	
	//*** Check Password ***//
	if(trim($Password) == "")
	{
		echo "<center><font color=red>** Plase input [Password]</font></center>";
		exit();
	}
	
	$host = "localhost";
	$user = "root";
	$pass = "123456";
	$db = "otop";

	$objConnect = mysql_connect($host,$user,$pass) or die("Error Connect to Database");
	$objDB = mysql_select_db($db);
	mysql_query("SET NAMES UTF8");


	//*** Check Username & Password ***//

	$strSQL = "SELECT * FROM Customers WHERE UserName = '".$Username."' and Passwords = '".$Password."' ";
	$objQuery = mysql_query($strSQL) or die ("Error Query [".$strSQL."]");
	$objResult = mysql_fetch_array($objQuery);
	
	
	if($objResult)
	{
		echo "Y";

		//*** Session ***//
		$_SESSION["CustomerID"] = $objResult["CustomerID"];
		$_SESSION["Username"] = $objResult["UserName"];
		$_SESSION["FirstName"] = $objResult["FirstName"];
		session_write_close();

		$cookie_name = "login";
		if(isset($_POST['cbRemember'])) {
			$value = $objResult["UserName"];
			$expire = time() + 30*24*60*60;
			setcookie($cookie_name, $value, $expire);
		}
		else {
			setcookie($cookie_name, '', 0);
		}

	}
	else
	{
		echo "<center><font color=red>** Username & Password is wrong</font></center>";
	}

	mysql_close($objConnect);
?>

<?php
    if(isset($_POST['cbRemember'])) {
            $value = $objResult["UserName"];
            $expire = time() + 30*24*60*60;
           setcookie($cookie_name, $value, $expire);
        }
        else {
            setcookie($cookie_name, '', 0);//<---ไม่ได้จำ log in จะอยู่ตรงนี้
        }
?>

<?php
<form name="frmMain">
<span id="mySpan"></span>
<table width="274" border="0" align="center">
  <tr>
    <th width="117">
      <div align="left">Username :</div></th>
    <th><input type="text" name="txtUsername" id="txtUsername" size="20"></th>
  </tr>
  <tr>
    <th colspan="2" bgcolor="#CCCCCC">&nbsp;</th>
    </tr>
  <tr>
    <th width="117">
      <div align="left">Password :</div></th>
    <th><input type="password" name="txtPassword" id="txtPassword" size="20"></th>
  </tr>
  <tr>
    <th colspan="2" bgcolor="#CCCCCC">&nbsp;</th>
  </tr>
  <tr>
    <th colspan="2">
    <label><input name="cbRemember" type="checkbox" id="cbRemember" value="cbRemember" />จดจำ ?</label></th>
    </tr> 
</table>
<br />
<br>
<center><input name="btnLogin" type="button" id="btnLogin" onclick="JavaScript:doCallAjax();" value="เข้าสู่ระบบ" /></center>
</form>
?>

<?php
<?
	session_start();

		if($_SESSION["Username"] == "")
	{
		header("location:login.php");
		exit();
	} 

?>
?>