This blog discusses the method of passing values from one page to another using Post Method in ASP.NET.
protected void Page_Load(object sender, EventArgs e)
{
string postbackUrl = "www.example.com"; // url where the user needs to be redirected.
string userName = Convert.ToString(Session["Loginid"]); // Assigned the value of user name in a string.
userName = EncryptSession.Encrypt(userName);// Encrypted the user name.
string url = "www.loginurl.com"; // url from where the user logins.
Response.Clear();
StringBuilder sb = new StringBuilder();
sb.Append("<html>");
sb.AppendFormat(@"<body onload='document.forms[""form""].submit()'>");
sb.AppendFormat("<form name='form' action='{0}' method='post'>", postbackUrl);
sb.AppendFormat("<input type='hidden' name='userName' value='{0}'>&", userName);
sb.AppendFormat("<input type='hidden' name='url' value='{0}'>", url);
// Other params go here
sb.Append("</form>");
sb.Append("</body>");
sb.Append("</html>");
Response.Write(sb.ToString());
Response.End();
}