Tons of information right here on the resource library
You need to be a little more specific on what your issue is. Is your issue giving an error message?
as mike said, can you be more specific with both your requirement and issue. There are differnt ways on demand can be used - the user can make selections within the appliaiton that will affect the report, the user can trigger an nprinting task isntead of a report.
I would test on your develpment workstation first - there are good examples and tutorials in the nptinting training environment