How to log in to the site using xNet?

Question

C++ / C#

The code

using (var request = new HttpRequest())
            {
                request.AddHeader(HttpHeader.Accept, "text/html,application/xhtml+xm…plication/xml;q=0.9,*/*;q=0.8");
                request.KeepAlive = true;
                request.AddHeader(HttpHeader.Referer, "https://fanty.online/start");
                request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:49.0) Gecko/20100101 Firefox/49.0";
                //Content-LengthCookie	sec_session_id = u9rut5e69djjunt…D % 7D; _ym_hostIndex = 0 - 2 % 2C1 - 0

                var reqParams = new RequestParams();
                reqParams["password"] = "244256";

                request.Cookies = new CookieDictionary()
    {
        {"sec_session_id", "u9rut5e69djjunt9un82i35cj5"}
    };

                string content = request.Post("https://fanty.online/start", reqParams).ToString();
                textBox1.Text = content;
            }

Everything seems to be simple, but it does not work. It doesn't even throw an error, but it doesn't log in either.