public ActionResult Login(string username, string password)
        {
            using (var db = new Db())
            {
                var matchingUser = db.Users.FirstOrDefault(x => x.Username == username && x.Password == password);
                if (matchingUser != null)
                    FormsAuthentication.RedirectFromLoginPage(matchingUser.Username, true);
            }

            var viewModel = new LoginViewModel
            {
                Message = "Invalid username or password."
            };
            return View(viewModel);
        }
 public ActionResult Login()
 {
     var viewModel = new LoginViewModel();
     return View(viewModel);
 }