xml create node (ルートノード、子ノード)

protected void Button1_Click(object sender, EventArgs e)//create xml
{
//Statement
XmlDocument x = new XmlDocument();
// Create
XmlDeclaration xd = x.CreateXmlDeclaration("1.0", "GB2312", null);
x.AppendChild(xd);
// Create the root node
XmlElement element = x.CreateElement("Books");
x.AppendChild(element);
//Add a child node of Books
XmlNode book = x.CreateElement("Book");
//add an element to Book
XmlElement bookname = x.CreateElement("bookname");
bookname.InnerText = "Three Kingdoms";
//add to nodes level by level
book.AppendChild(bookname);
element.AppendChild(book);
x.AppendChild(element);
// save the document (if it already exists, update it; if not, create it)
x.Save(@"F:/Books.xml");
}