POST запрос на принятие Cookies

private static string _POST(string uri, string data)
        {
            HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(uri);
            req.Method = "POST";
            req.Host = @"www.seasonvar.ru";
            req.Accept = @"text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8";
            req.Headers.Add("Accept-Encoding", @"gzip, deflate");
            req.Headers.Add("Accept-Language", @"ru-RU,ru;q=0.8,en-US;q=0.5,en;q=0.3");
            req.UserAgent = @"Mozilla/5.0 (Windows NT 6.1; WOW64; rv:20.0) Gecko/20100101 Firefox/20.0";
            req.Referer = @"http://www.seasonvar.ru/?mod=login";
            req.ContentType = @"application/x-www-form-urlencoded";
            req.AutomaticDecompression = DecompressionMethods.Deflate | DecompressionMethods.GZip;
 
            byte[] byteArray = Encoding.UTF8.GetBytes(data);
            req.ContentLength = byteArray.Length;
 
            Stream dataStream = req.GetRequestStream();
            dataStream.Write(byteArray, 0, byteArray.Length);
            dataStream.Close();
 
            HttpWebResponse res = (HttpWebResponse)req.GetResponse();

Headers {Transfer-Encoding: chunked
Connection: keep-alive
Content-Type: text/html; charset=utf8
Date: Sat, 08 Jun 2013 11:13:32 GMT
Set-Cookie: svd=1370690039; expires=Mon, 08-Jul-2013 11:13:59 GMT; path=/, brand=b_cx; expires=Sun, 09-Jun-2013 11:13:59 GMT; path=/; domain=.seasonvar.ru
Server: nginx
Content-Encoding: 
 
}