Hi..Hope it helps u
String Mymsg = String.Format("110", authCode, DateTime.Now.ToString(), txtFirstName.Text + " " + txtLastName.Text, txtPayment.Text);
Session["Successmsg"] = Mymsg;
Response.Redirect("Thank.aspx");
In Thank.aspx.cs page:
Label2.Text = (String)(Session["Successmsg"]);
Session.Abandon();
Session.Clear();