read this page: http://www.php.net/manual/en/function.setcookie.php
easy way to see where the val is stored is to do a print_r($_COOKIE)
// value is in $_COOKIE['Kullanici'];
setcookie("Kullanici",$username,$time()+360000);
// another way is to store values as an array
// value is in $_COOKIE['Kullanici']['username']
setcookie("Kullanici[username]",$username,$time()+360000);
// value is in $_COOKIE['Kullanici']['password']
setcookie("Kullanici[password]",$password,$time()+360000);