XML C#

using System;
using System.Linq;
using System.Xml;
using System.Xml.Linq;
using System.Collections;
using System.Collections.Generic;
using System.Xml.XPath;
public class MainClass{
   public static void Main(){
            
      XmlDocument document = new XmlDocument();
      document.Load("domainBooks.xml");
      XPathNavigator navigator = document.CreateNavigator();
      
      navigator.MoveToChild("bookstore", "http://www.domain.com/books");
      navigator.MoveToChild("book", "http://www.domain.com/books");
      navigator.MoveToChild("price", "http://www.domain.com/books");
      
      XmlWriter attributes = navigator.CreateAttributes();
      
      attributes.WriteAttributeString("discount", "1.00");
      attributes.WriteAttributeString("currency", "USD");
      attributes.Close();
      
      navigator.MoveToParent();
      Console.WriteLine(navigator.OuterXml);
   }
}