XML node

            XmlNamespaceManager nsmgr = new XmlNamespaceManager(xmlFile.NameTable);
            nsmgr.AddNamespace("smap", "http://schemas.microsoft.com/AspNet/SiteMap-File-1.0");
            string xpath = "//smap:siteMapNode[@url=\"{0}\"]";
            string url = "~/Index";

            return GetSiteMapNodeFromElement((XmlElement)xmlFile.SelectSingleNode(String.Format(xpath, url), nsmgr));

XML C# samples

XDocument xdoc = XDocument.Load("data.xml");
var lv1s = xdoc.Root.Descendants("level1"); 
var lvs = lv1s.SelectMany(l=>
     new string[]{ l.Attribute("name").Value }
     .Union(
         l.Descendants("level2")
         .Select(l2=>"   " + l2.Attribute("name").Value)
      )
    );
foreach (var lv in lvs)
{
   result.AppendLine(lv);
}

void Main()
{
    XElement rootElement = XElement.Load(@"c:\events\test.xml");

    Console.WriteLine(GetOutline(0, rootElement));  
}

private string GetOutline(int indentLevel, XElement element)
{
    StringBuilder result = new StringBuilder();

    if (element.Attribute("name") != null)
    {
        result = result.AppendLine(new string(' ', indentLevel * 2) + element.Attribute("name").Value);
    }

    foreach (XElement childElement in element.Elements())
    {
        result.Append(GetOutline(indentLevel + 1, childElement));
    }

    return result.ToString();
}

XDocument xdoc = XDocument.Load("data.xml"));
var lv1s = from lv1 in xdoc.Descendants("level1")
           select new { 
               Header = lv1.Attribute("name").Value,
               Children = lv1.Descendants("level2")
           };


foreach (var lv1 in lv1s){
        result.AppendLine(lv1.Header);
        foreach(var lv2 in lv1.Children)
             result.AppendLine("     " + lv2.Attribute("name").Value);
}