Informix ISQL and report ranges (user input)

I've JUST purchased ISQL and everything looks straight forward enough. However it's not clear to me how one goes about getting it set up so that the end user can specify begin and end ranges for a report. For example, suppose I set up a report for line items using a table of all line items. But I want the user to be able to put in begin and end dates so that only a subset of rows are reported. What should I do. I can't easily see how to do this from the manual. But surely the facility is there... Thanks, Kate