Get data from another page

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

namespace WebFormApplication
{
    public partial class Validate : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            //before getting data dont forget to put postbackurl of this page in previuos page button property
            string username = ((TextBox)PreviousPage.FindControl("txtUsername")).Text;
            string password= Request.Form["txtPassword"];
            if(username=="admin" && password=="admin")
            {
                Response.Write("Login Successfuly");
            }
            else
            {
                Response.Write("Invalid Login");
            }
        }
    }
}