I tried what you suggested and that did not work. I am inserting the
whole code that I have in my form (I have created a windows application
- the form has a textbox and a button). Please let me know what I have
done wrong.

public partial class Form1 : Form
   {
       public Form1()
       {
           InitializeComponent();
       }

       private CookieContainer cookiejar = new CookieContainer();

       public string ScrapeURL(string URL)
       {
           string viewstate = HttpUtility.UrlEncode(viewstatevalue);
           StringBuilder data = new StringBuilder();
           data.Append("VAM_Group=");
           data.Append("&__VIEWSTATE=" + viewstate);
           data.Append("&ctlSignon:txtUserID=userid");
           data.Append("&ctlSignon:txtPassword=password");
           data.Append("&ctlSignon:ddlSignonDestination=");
           data.Append("&ctlSignon:chkMakeDefaultPage=on");
           data.Append("&ctlSignon:btnLogin=Login");
           data.Append("&TestJavaScript=OK");

           byte[] bBuffer;

           bBuffer = Encoding.UTF8.GetBytes(data.ToString());

           HttpWebRequest req =
             (HttpWebRequest)WebRequest.Create(URL);
           req.Method = "POST";
           req.ContentType = "application/x-www-form-urlencoded";
           req.ContentLength = bBuffer.Length;
           req.Credentials = CredentialCache.DefaultCredentials;
           req.KeepAlive = true;
           req.CookieContainer = this.cookiejar;

           Stream swOut = req.GetRequestStream();
           swOut.Write(bBuffer,0,bBuffer.Length);

           HttpWebResponse resp = (HttpWebResponse)req.GetResponse();
           Stream sr = resp.GetResponseStream();
           string result = new StreamReader(sr).ReadToEnd();

           return result;
       }

       private void button1_Click(object sender, EventArgs e)
       {
           textBox1.Text =
ScrapeURL("https://online.texanscu.org/texans/login.aspx");
       }
   }

I appreciate your help.

Thanks,
NeelG