如何从cookieContainer HttpWebrequest将网站加载到Webrowser

我尝试通过Httprequest登录网站，并回复一些信息。我保存了 Cookie 响应。那么我怎么知道我登录成功了，我尝试通过 Cookie 加载带有新表单的网站，但它不是登录。所以你能帮我吗...这是我的代码：

登录代码：

HttpWebRequest getRequest = (HttpWebRequest)WebRequest.Create(new Uri("https://www.nike.com/profile/login?Content-Locale=en_US"));
            getRequest.CookieContainer = new CookieContainer();
            getRequest.CookieContainer.Add(myLoginCookies);
            getRequest.Method = WebRequestMethods.Http.Post;
            getRequest.ContentType = "application/x-www-form-urlencoded; charset=UTF-8";
            getRequest.UserAgent = userAgent;
            getRequest.Referer = "http://www.nike.com/";
            getRequest.Accept = "application/json, text/javascript, */*; q=0.01";
            getRequest.KeepAlive = true;
            string postData = "login=" + username + "&rememberMe=false&password=" + password;
            try
            {
                using (StreamWriter writer = new StreamWriter(getRequest.GetRequestStream()))
                    writer.Write(postData.ToString());
               HttpWebResponse getResponse = (HttpWebResponse)getRequest.GetResponse();
               using (StreamReader reader = new StreamReader(getResponse.GetResponseStream()))
                    returnData = reader.ReadToEnd();
                //MessageBox.Show(returnData);
               myLoginCookies.Add(getResponse.Cookies);
                if (myLoginCookies.Count > 1)
                {
                    return new NikeStore(myLoginCookies, returnData);                
                }
                else
                {
                    MessageBox.Show("login failed");
                    return null;
                }
            }
            catch (WebException ex)
            {
                MessageBox.Show(ex.Message);
                return null;
            }

和这个代码加载网站通过 Cookie 返回

public Form_OpenCart(CookieCollection oCookie, string url_page)
        {
            InitializeComponent();
            foreach (Cookie cook in oCookie)
            {
                cookie.Add(cook);
            }
            url = url_page;
        }
        private void Form_OpenCart_Load(object sender, EventArgs e)
        {
            url = "http://store.nike.com/us/en_us/";
            if (cookie != null)
            {
                foreach (Cookie cook in cookie)
                {
                    cookie_string += cook.ToString() + ";";
                    InternetSetCookie(url, cook.Name, cook.Value);
                }
                webBrowser1.Navigate(url);               
            }
            else
            {
                MessageBox.Show("huhuhu");
            }

请帮助我。我尝试了很多，但我无法成功。