A beginner's guide to XPath

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Xml;

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            XmlDocument document = null;
            XmlNodeList nodeList = null;
            XmlNode node = null;

            // Try and load xml data into an Xml document object and throw an
            // error message if this fails
            try
            {
                document = new XmlDocument();
                document.Load("Data.xml");
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error loading 'Data.xml'. Exception: " + ex.Message);
            }

            // If the above was successful...
            if (document != null)
            {
                #region Retrieve a list of book titles
                MessageBox.Show("Starting to list book titles...");
                try
                {
                    // Try and retrieve all book nodes
                    nodeList = document.SelectNodes("/books/book");

                    foreach (XmlNode book in nodeList)
                    {
                        // Show a message with the book title
                        MessageBox.Show(book.SelectSingleNode("title").InnerText);
                    }
                }
                catch (Exception ex)
                {
                    // Error whilst retrieving book data
                    MessageBox.Show("Error whilst retrieving book data. Error message: " + ex.Message);
                }
                MessageBox.Show("Finishing list of book titles...");
                #endregion

            }
        }
    }
}