RS subreport problem

Hi, I need your help.
I have report with subreport. Report has one information and if you click to one field I need subreport open and show another information.
I created this report but the problem is User complain that he cannot go back to main report there is no back button inside html viewer.(it exists in design).
I have 2 choices:
1. open subreport in new window
2. create link inside subreport to main report.

1. I couldn't find how to do it. because I need to pass the parameters from main report to subreport in URL string.
2. I created parameters in subreport and pass to them main report param. whan I click on the "return to main report" text box it return to main report. but I have 2 issues with this scenario. 1) I need to hide parameters (If I hide them by removing Promt propery and set the default value. whenI run report from the main I got error parameter is read-only. 2) If I don't hide them I see the parameters what I don't need but another problem it opens the main report and hide the parameter panel (I am talking about HTML viewer).

Please let me know if you done someting simmular.
Thanks a lot.

thank I figured it out.