how to get user defined attributes when writing datset data to xml in asp.net c#

Question

Hi  , Iam able to write dataset data to xml file using ds.WriteXml(Request.PhysicalApplicationPath + "\\XML\\ds.xml",XmlWriteMode.IgnoreSchema);

in which i want the node attribute names sholud be user defined 

please tell me how to do this

 i want user defined : rootnode name , node name , attribute name etc........(.but the data must be from dataset)

thanks in advance....