1.Create DataTable with Required columns in a xml
DataTable dt = new DataTable();
dt.Columns.Add("Name");
2.Add rows to Datatable
DataRow dr = dt.NewRow();
dr["Name"] = "XYZ";
dt.Rows.Add(dr);
4.Add that datatable to Dataset
DataSet ds = new DataSet();
ds.Tables.Add(dt);
5.Directly use Ds write.
ds.WriteXml("d:\\1.xml");