public void SaveUser(LinqToSql.td_Users user)
        {
            try
            {
                LINQContext _db = new LINQContext();  
                user.user_Time = DateTime.Now;
                _db.td_Users.Attach(user);
                _db.SubmitChanges();
            }
            catch(Exception e)
            {
                MessageBox.Show(e.Message);
            }
        }