Passing a value to a report parameter
To pass a value to the report parameter, use the SetParameterValue method of the Report object. This method was described in details in the "Working with Windows.Forms" chapter.
To use this method in ASP.NET, you need to create the event handler for the StartReport event of the WebReport component. The report can be accessed through the WebReport.Report property:
webReport1.Report.SetParameterValue("MyParam", 10);