passing parameter from webform to crystal report

In the crystal report, create Parameter Fields for the parameters you want to pass at runtime.

Then in your code, where you create the report instance like for example

TestReport myReport = new TestReport();

you can pass the parameter in using the SetParameterValue(string ParameterName, object ParameterValue, string SubReportName) method.

Example :

myReport.SetParameterValue("MyParameter", 123, "MySubReport.rpt");