How to get selected node and its child value from treeview?

public BindingList<TreeNode> bindingList;

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics;
using System.Drawing;
using System.IO;
using System.Windows.Forms;

namespace TestForm1
{
    /// <summary>
    /// Test data grid with BindingList.
    /// </summary>
    public partial class Form8 : Form
    {
        public BindingList<diskClass> bindingList;

        public Form8()
        {
            InitializeComponent();

            // Allow user to resize column widths.
            this.dataGridView1.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.None;
            this.dataGridView1.AllowUserToAddRows = false;
        }

        /// <summary>
        /// Fill the BindingList and set the dataGridView1.DataSource.
        /// </summary>
        private void button1_Click(object sender, EventArgs e)
        {
            bindingList = new BindingList<diskClass>();
            bindingList.AllowNew = true;
            bindingList.AllowRemove = true;

            if (this.dataGridView1.DataSource != null)
            {
                this.dataGridView1.DataSource = null;
            }

            this.AddTestData(@"C:\Temp");
         }

        /// <summary>
        /// Add rows with directory names.
        /// </summary>
        private void AddTestData(string dirString)
        {
            string[] dirs = Directory.GetDirectories(dirString);
            int number = 1;

            foreach (string dir in dirs)
            {
                DirectoryInfo di = new DirectoryInfo(dir);
                TreeNode node = new TreeNode(dir, 0, 1) { Checked = true, Name = di.Name};

                var item = new diskClass();
                item.Number = number++;
                item.Name = node.Name;
                item.Path = node.Text;
                bindingList.Add(item);
            }

            this.dataGridView1.DataSource = bindingList;
            this.dataGridView1.Columns[0].Frozen = true;
        }

        private void buttonDelete_Click(object sender, EventArgs e)
        {
            if (this.dataGridView1.CurrentRow != null)
            {
                this.bindingList.RemoveAt(this.dataGridView1.CurrentRow.Index);
            }
        }

        private void buttonAdd_Click(object sender, EventArgs e)
        {
            var item = new diskClass();
            bindingList.Add(item);
        }
    }

    public class diskClass
    {
        public int Number { get; set; }
        public string Name { get; set; }
        public string Path { get; set; }
    }
}