hello Jothi, in response to your questions here and those that you posted on this blog you can create a dynamic top n report where the sort (asc or desc) and the group and the measure are parameterized. the end user would use the Parameter Panel as opposed to the pop-up parameter dialogue.
please have a look at the attached report where the Report > Group Sort Expert and parameters and a formula for the measure is used for this process. you need to unzip the contents and change the .txt extension of the file to .rpt.
this report is not documented so please do look at each component used in the report. this report allows the end user to change the group, the measure, the N based on that measure, and whether that N is Asc or Desc using a sort formula. again, please have a look through the report in detail to get an idea of what it does so you can apply this technique to your report.
like in the case of this particular attached report, you do not have to build the top n into the query as the Group Sort Expert takes care of this. however, when you do not do this, you are bringing back all values and then the groups are just hidden in the report. however, if you've already got a view or proc that your report is based on, then this is an option for you that does not involve any changes to that view or proc.
as per Abhilash's suggestion to use webelements, there is a user guide available on that page that he provided the link for. it is free but requires more set up and a more advance report creation workflow and some set up on the boe side as per the user guide.
cheers,
jamie