private void CreateUser()
        {
            var formCreationUser = new FormCreationUser(_rewards);

            formCreationUser.ShowDialog(this);

            if (formCreationUser.DialogResult == DialogResult.OK)
            {
                _users.Add(new User(formCreationUser.FirstName, formCreationUser.LastName, formCreationUser.BirthDay,
                                    formCreationUser.Rewards));
            }
        }
        private void EditUser()
        {
            if (ctlUsers.SelectedCells.Count > 0)
            {
                User user = (User)ctlUsers.SelectedCells[0].OwningRow.DataBoundItem;

                var formEditingUser = new FormCreationUser(user, _rewards);

                formEditingUser.ShowDialog(this);

                if (formEditingUser.DialogResult == DialogResult.OK)
                {
                    user.FirstName = formEditingUser.FirstName;
                    user.LastName  = formEditingUser.LastName;
                    user.BirthDay  = formEditingUser.BirthDay;

                    ctlUsers.Refresh();
                }
            }
        }