private void registrar_Click(object sender, EventArgs e)
        {
            usuario.Text     = "";
            contrasenia.Text = "";
            RegistroPasoUno form = new RegistroPasoUno();

            form.Show();
        }
        private void registrarseToolStripMenuItem_Click(object sender, EventArgs e)
        {
            RegistroPasoUno form = new RegistroPasoUno();

            form.Show();
        }