protected void SearchButton_Click(object sender, EventArgs e)
        {
            // Create filter
            UserSearchDTO criteria = new UserSearchDTO();

            // set filter from ui controls
            criteria.FirstName = this.FirstNameTextBox.Text;
            criteria.LastName = this.LastNameTextBox.Text;
            using (UserManager um = new UserManager())
            {
                // get users by fileter
                List<User> users = um.FindUsersByCriteria(criteria);
                this.UserGridView.DataSource = users;
                this.UserGridView.DataBind();

            }
        }
 public List<User> FindUsersByCriteria(UserSearchDTO criteria)
 {
     return udao.FindUsersByCriteria(criteria);
 }