there is no need to convert xmlWriter class.
string
xmlFile = System.Web.
HttpContext.Current.Server.MapPath(
"~/App_Data/Candidates.xml");
xmldoc = new XmlDocument();
xmldoc.Load(xmlFile);
root = xmldoc.DocumentElement;
try
{
XmlNode CandidateNode = xmldoc.CreateNode(XmlNodeType.Element, "Candidate", "");
XmlNode id = xmldoc.CreateNode(XmlNodeType.Element, "CandidateId", "");
id.InnerText = "1";
CandidateNode.AppendChild(id);
XmlNode subPositionId = xmldoc.CreateNode(XmlNodeType.Element, "SubPositionId", "");
subPositionId.InnerText = candidate.PositionId.ToString();
CandidateNode.AppendChild(subPositionId);
XmlNode firstName = xmldoc.CreateNode(XmlNodeType.Element, "FirstName", "");
firstName.InnerText = candidate.FirstName;
XmlNode lastName = xmldoc.CreateNode(XmlNodeType.Element, "LastName", "");
lastName.InnerText = candidate.LastName;
CandidateNode.AppendChild(firstName);
CandidateNode.AppendChild(lastName);
root.AppendChild(CandidateNode);
xmldoc.Save(xmlFile);
This will help you.