Ok Bishal, as I say you don't need to install anything else, you have all you need to start the IBM Admin Server in your IHS.
To start IBM Admin Server you need to launch the next command from IHS HOME:
httpd -f conf\admin.conf
By default the server starts at 8008, then check admin_error.log.
To register as a service, with and administrator provileges count, start a cmd window and go to IHS_HOME (C:\IBM\HTTPServer\bin)
httpd.exe -k install -f conf\admin.conf -n "IBM HTTPv8 ADMIN"
where -n parameter is service name so put what you want.
to uninstall the service:
httpd.exe -k uninstall -n "IBM HTTPv8 ADMIN"
Try and let us.
Regards