Send Sms Using way2sms api

I want to send SMS using way2sms. I have tried following code

login.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace WebApplication1
{
  public partial class Login : System.Web.UI.Page
  {
    protected void Page_Load(object sender, EventArgs e)
    {

    }

    protected void btnconnect_Click(object sender, EventArgs e)
    {
        Session["id"] = txtmobileno.Text;
        Session["pw"] = txtpw.Text;
        Response.Redirect("/send.aspx");
    }
  }
 }

send.aspx.cs

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.IO;
using System.Net;
using System.Text;
using System.Text.RegularExpressions;

namespace WebApplication1
{
  public partial class send : System.Web.UI.Page
  {
    string mbno, mseg, ckuser, ckpass;
    private HttpWebRequest req;
    private CookieContainer cookieCntr;
    private string strNewValue;
    public static string responseee;
    private HttpWebResponse response;

    protected void Page_Load(object sender, EventArgs e)
    {
        if (Session["id"] == null && Session["pw"] == null)
        {
            Server.Transfer("login.aspx");
        }
        connect();

        try
        {

            lblError.Text = "";
            lblError.Visible = false;
            if (!(IsPostBack))
            {
                btnSend.Attributes.Add("onclick", "return Validate('" + txtTo.ClientID + "','" + txtMessage.ClientID + "');");
                txtMessage.Attributes.Add("onchange", "TextChange('" + txtMessage.ClientID + "','" + lblLeft.ClientID + "');");
                txtMessage.Attributes.Add(