check cookie

if (isset($_COOKIE['ID_my_site']))

//if its there,logs you in and directs to mainpage
{
$_username=$_COOKIE['ID_my_site'];

$_pass= $_COOKIE['Key_my_site'];

$check=mysql_query("Select * From users WHERE username=
'$username'") or die (mysql_error());

while ($info=mysql_fetch_array($check))
{
if ($pass != "info['password'])

{

}

else
{
header("Location:main.html");

}