Create Custom Permission in Object Level

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using CustomPermission.Model;

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

        }
        protected void cvLogin_ServerValidate(object source, ServerValidateEventArgs args)
        {
            args.IsValid = (from u in DataContext.Context.Users
                            where u.Username == txtUsername.Text && u.Password == txtPassword.Text
                            select u).Count() != 0;
        }

        protected void btnLogin_Click(object sender, EventArgs e)
        {
            if (Page.IsValid)
            {
                FormsAuthentication.RedirectFromLoginPage(txtUsername.Text, chkRemember.Checked);
            }
        }
    }
}