how do i create DATASET in this example?

Question

hi
i have a lot of problem with this example.
when i try a program like this, i don't know how i should create these below code?

 private void Form1_Load(object sender, EventArgs e)
        {
            this.OrdersDataSet.ReadXml("Orders.xml");
            this.OrderDetailsDataSet.ReadXml("OrderDetails.xml");
          
        }

void LocalReport_SubreportProcessing(object sender, SubreportProcessingEventArgs e)
        {
            e.DataSources.Add(new ReportDataSource("OrderDetailsDataSet_OrderDetails", OrderDetailsDataSet.Tables[0]));
        }

please help me.
this problem countinue in many example for me.
i do not realize that how  should i  create this data set?(i think the program should automaticly create it ,but it didn't happen!)why?
OrderDetailsDataSet.ReadXml("OrderDetails.xml");
when i write this code ,program give me error,that  OrderDetailsDataSet doesn't exist.
http://www.gotreportviewer.com/masterdetail/SubreportInList.zip