Using Session Manager User Credentials active or in active

Question

How to validate user name and password Using Session manager? I need 3-tier architecture code

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


    }
    protected void btnLogin_Click(object sender, EventArgs e)
    {
        Constants con = new Constants();

        Users user = new Users();
        string message = "";
        if (user.AuthenticateUser(txtUserName.Text, txtPassword.Text, out message))
        {
            FormsAuthentication.RedirectFromLoginPage(txtUserName.Text, true);
            Response.Redirect("Home.aspx");
        }
        else
        {

            //error_msg.Text = message;
            //dialog_box_extender.Show();


        }


    }
}

Here i need to call my stored procedure through web.config