private void BtnSignIn_Click(object sender, EventArgs e)
        {
            AppUser appUser = new AppUser()
            {
                UserName     = txtUserName.Text,
                UserPassword = txtUserPassword.Text
            };

            bool loginControll = loginController.UserSignInControll(appUser);

            if (loginControll)
            {
                HelperStaticClass.appUserStatic = loginController.AppUserGet(appUser);

                if (HelperStaticClass.guestsDictionery.Count >= 1)
                {
                    ReservationFinalScreen reservationFinalScreen = new ReservationFinalScreen();
                    reservationFinalScreen.Show();
                }
                else
                {
                    ReservationScreen reservationScreen = new ReservationScreen();
                    reservationScreen.Show();
                }
                this.Hide();
            }
            else
            {
                MessageBox.Show("Invalid password or username!");
            }
        }