private void btnSavecourse_Click(object sender, EventArgs e)
 {
     Form1.course Auxcurse = new Form1.course();
     Auxcurse.courseId = txtIDcourse.Text;
     Auxcurse.creditos = int.Parse(txtCreditos.Text);
     Principal.root.asignaturas.Add(Auxcurse);
     MessageBox.Show("Curso agregado");
 }
        private void btnEnrollstudent_Click(object sender, EventArgs e)
        {
            Form1.course AuxCurse = new Form1.course();

            AuxCurse = Principal.root.asignaturas.Where(p => p.courseId == cmbCursosDisponibles.SelectedItem.ToString()).FirstOrDefault();

            foreach (Form1.course curse in Principal.root.asignaturas)
            {
                if (curse.courseId == cmbCursosDisponibles.SelectedItem.ToString())
                {
                    curse.students.Add(EstudianteActual);
                    return;
                }
            }

            MessageBox.Show("estudiante inscrito");
        }