XML C#

using System;
using System.IO;
using System.Xml;
using System.Xml.XPath;
using System.Xml.Xsl;
public class Sample
{
    public static void Main()
    {
        XmlDocument doc = new XmlDocument();
        doc.Load("books.xml");
        XmlElement root = doc.DocumentElement;
        root.FirstChild.LastChild.InnerText = "12.95";
        XPathNavigator nav = root.CreateNavigator();
        XslTransform xslt = new XslTransform();
        xslt.Load("output.xsl");
        XmlTextWriter writer = new XmlTextWriter("books.html", null);
        xslt.Transform(nav, null, writer, null);
    }
}