function FindbyAttValue(snd:IXMLNode;ndname,attName:string;attvalue:string):IXMLNode;
Var I:integer;
    s:string;
begin
  Result:=nil;
  For I:=0 to snd.ChildNodes.Count -1 do
    If comparetext(ndname,snd.ChildNodes[I].NodeName)=0 then begin
      s:=snd.ChildNodes[I].Attributes[attname];
      If Comparetext(attvalue,s)=0 then begin
        Result:=snd.ChildNodes[I];
        break;
      end;
    end;
  If Result=nil then
    If snd.ChildNodes.Count > 0 then
      For I:=0 to snd.ChildNodes.Count -1 do begin
        Result:=FindbyAttValue(snd.ChildNodes[I], ndname,attname,attvalue);
        If Result <> nil then break;
      end;
end;    

var node:IXMLNode;
begin
  node:=FindNodeByValue(XMLDocument.DocumentElement, 'Chapter','chapterno','0');
  node.addchild('Section');//加入TagName為"Section"之child node
end;