protected void Button1_Click(object sender, EventArgs e)
{
string path = MapPath("XMLFile.xml");
XmlDocument xmldoc = new XmlDocument();
xmldoc.Load(path);
XmlElement newelement = xmldoc.CreateElement("poems");
XmlElement xmlauthor = xmldoc.CreateElement("author");
XmlElement xmltitle = xmldoc.CreateElement("title");
XmlElement xmlcontent = xmldoc.CreateElement("content");
xmlauthor.InnerText = TextBox1.Text.ToString();
xmltitle.InnerText = TextBox2.Text.ToString();
xmlcontent.InnerText = TextBox3.Text.ToString();
newelement.AppendChild(xmlauthor);
newelement.AppendChild(xmltitle);
newelement.AppendChild(xmlcontent);
xmldoc.DocumentElement.AppendChild(newelement);
xmldoc.Save(path);
}