Reports Parameters

Hi

I've been looking about and can't seem to find anything that helps me out on this, I know this is probably something simple but my knowledge of the code structure and syntax is lacking as I've only just started using this and on the bottom of the learning curve

with the reports there is a Parameters tab,

how do I reference these parameters within a report?
I've tried a couple fo things and keep on getting an unknown source java error

thanks
Mike