private void hướngDẫnToolStripMenuItem_Click(object sender, EventArgs e)
        {
            HuongDan frm = new HuongDan();

            frm.Show();
        }
 private void hướngDẫnToolStripMenuItem_Click(object sender, EventArgs e)
 {
     HuongDan frm = new HuongDan();
     frm.Show();
 }