$options = array(
                'http' =>
                    array(
                        'method' => 'POST',
                        'header' => 'Content-type: application/x-www-form-urlencoded;charset=UTF-8',
                        'content' => 'user=hello&password=world',
                        'ignore_errors' => true
                    )
            );
            $context = stream_context_create($options);

            $result = file_get_contents('http://site.ru/blabla', false, $context);