Writing a Dataset to xml including extra element

Hi i am converting rss into xml using Datable. First i am reading the rss and converting into DataTable. Datatable is then converting into XML.

       try
        {
            DataTable tbl = new DataTable();
            tbl.Columns.Add("id");
            tbl.Columns.Add("product_name");
            XmlDocument doc = new XmlDocument();
            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.Load("");
            XmlNodeList itemNodes = xmlDoc.SelectNodes("//rss/channel/item");
            foreach (XmlNode itemNode in itemNodes)
            {
                DataRow row = tbl.NewRow();
                XmlNode idNode = itemNode.SelectSingleNode("id");
                XmlNode product_nameNode = itemNode.SelectSingleNode("product_name");

                if (idNode != null && product_nameNode != null)
                {
                    row[0] = idNode.InnerText;
                    row[1] = product_nameNode.InnerText;


                }
                tbl.Rows.Add(row);
                // tbl.Rows.Add(row);
            }

            DataSet dataSet = new DataSet("Products");
            tbl.TableName = "Product";
            dataSet.Tables.Add(tbl);
            // Save to disk

            dataSet.WriteXml("");

            dataSet.Clear();
            tbl.Clear();
            dataSet.Tables.Remove(tbl);


        }
        catch (Exception ex)
        {
            // Console.WriteLine(ex.Message);
            // Console.Read();

        }

The final XML is like that

 <Products>
   <Product>
       <id>121385</id> 
       <product_name>ABC</product_name> 
   <Product>
   <Product>
       ...
   <Product>
   <Product>
        ...
   <Product>
<Products>  

The result is fine but i want to add one more node, i.e totalcount just after the

<totalcount>1000</totalcount>

It should be like that.

  <Products>
    <totalcount>1000</totalcount>
    <Product>
           ...
    <Product>
    <Product>
           ...
    <Product>
 <Products> 

How can i add totalcount element?