关于Cookie和Session共同实现登录功能的问题

  private void postTestButton_Click(object sender, EventArgs e)
        {
            PostByWebRequest();
        }
        private void PostByWebRequest()
        {
            try
            {
                CookieContainer cookieContainer = new CookieContainer();                ///////////////////////////////////////////////////
                // 1.打开 MyLogin.aspx 页面，获得 GetVeiwState & EventValidation
                ///////////////////////////////////////////////////                
                // 设置打开页面的参数
                string URI = "http://localhost:1165/WebTest/MyLogin.aspx";
                HttpWebRequest request = WebRequest.Create(URI) as HttpWebRequest;
                request.Method = "GET";
                request.KeepAlive = false;                // 接收返回的页面
                HttpWebResponse response = request.GetResponse() as HttpWebResponse;
                System.IO.Stream responseStream = response.GetResponseStream();
                System.IO.StreamReader reader = new System.IO.StreamReader(responseStream,Encoding.UTF8);
                string srcString = reader.ReadToEnd();                // 获取页面的 VeiwState                
                string viewStateFlag = "id=\"__VIEWSTATE\" value=\"";
                int i = srcString.IndexOf(viewStateFlag) + viewStateFlag.Length;
                int j = srcString.IndexOf("\"", i);
                string viewState = srcString.Substring(i, j - i);                // 获取页面的 EventValidation                
                string eventValidationFlag = "id=\"__EVENTVALIDATION\" value=\"";
                i = srcString.IndexOf(eventValidationFlag) + eventValidationFlag.Length;
                j = srcString.IndexOf("\"", i);
                string eventValidation = srcString.Substring(i, j - i);                ///////////////////////////////////////////////////
                // 2.自动填充并提交 MyLogin.aspx 页面
                ///////////////////////////////////////////////////
                // 提交按钮的文本
                string submitButton = "登录";                // 用户名和密码
                string userName = "1";
                string password = "1";                // 将文本转换成 URL 编码字符串
                viewState = System.Web.HttpUtility.UrlEncode(viewState);
                eventValidation = System.Web.HttpUtility.UrlEncode(eventValidation);
                submitButton = System.Web.HttpUtility.UrlEncode(submitButton);                // 要提交的字符串数据。格式形如:user=uesr1&password=123
                string formatString = "userName={0}&password={1}&loginButton={2}&__VIEWSTATE={3}&__EVENTVALIDATION={4}";
                string postString = string.Format(formatString, userName, password, submitButton, viewState, eventValidation);                // 将提交的字符串数据转换成字节数组
                byte[] postData = Encoding.ASCII.GetBytes(postString);                // 设置提交的相关参数
                request = WebRequest.Create(URI) as HttpWebRequest;
                request.Method = "POST";
                request.KeepAlive = false;
                request.ContentType = "application/x-www-form-urlencoded";
                request.CookieContainer = cookieContainer;
                request.ContentLength = postData.Length;                // 提交请求数据
                System.IO.Stream outputStream = request.GetRequestStream();
                outputStream.Write(postData, 0, postData.Length);
                outputStream.Close();                // 接收返回的页面
                response = request.GetResponse() as HttpWebResponse;
                responseStream = response.GetResponseStream();
                reader = new System.IO.StreamReader(responseStream,Encoding.GetEncoding("GB2312"));
                srcString = reader.ReadToEnd();                ///////////////////////////////////////////////////
                // 3.打开 Default.aspx 页面
                ///////////////////////////////////////////////////
                // 设置打开页面的参数
                URI = "http://localhost:1165/WebTest/Default.aspx";
                request = WebRequest.Create(URI) as HttpWebRequest;
                request.Method = "GET";
                request.KeepAlive = false;
                request.CookieContainer = cookieContainer;                // 接收返回的页面
                response = request.GetResponse() as HttpWebResponse;
                responseStream = response.GetResponseStream();
                reader = new System.IO.StreamReader(responseStream, Encoding.UTF8);
                srcString = reader.ReadToEnd();                ///////////////////////////////////////////////////
                // 4.分析返回的页面
                ///////////////////////////////////////////////////
                // ...... ......
            }
            catch (WebException we)
            {
                string msg = we.Message;
            }          }
这个是在WinForm里的代码，为什么不能打开http://localhost:1165/WebTest/MyLogin.aspx和http://localhost:1165/WebTest/Default.aspx这二个网站页面（存在一个解决方案里）？谁能提供Session和Cookie共同完成登录系统（可以自动登录）的源代码呀？
还有一个问题是HttpCookie是不是在客户端不好使，与Cookie相比，二者分别用在那里比较好哦？
谢谢回答！