Stimulsoft.Report.StiReport stiReport = new Stimulsoft.Report.StiReport();
stiReport.Load("Reports//YourReportName.mrt");

stiReport.RegBusinessObject("Name1", List1);
stiReport.RegBusinessObject("Name2", List2);
stiReport.RegBusinessObject("Name3", List3);

DataSet ds = new DataSet();
ds.Tables.Add(YourDataTable);
stiReport.RegData(ds);

stiReport.Dictionary.Variables["Today"].Value = DateTime.Now.ToShortDateString();

stiReport.Design();

stiReport.Compile();
stiReport.Render();
stiViewer.Report = stiReport;
stiViewer.Show();

public class Master (){
   public int Id {get; set;}
   public string Name {get; set;}
   public Icollection<Detail>Details {get; st;}
}

public Class detail(){
  public int code {get; set;}
  public string datadetail {get; set;}
}