To setup parameters for a user to enter, go to the Field Explorer screen, right click on parameter fields and select new. The screen will ask for a name, a prompt and a type. When you run your report, the prompt will appear and give the user a field to enter the data.
For you, you could call it fromdate. The prompt would be 'enter the from date' and it has a type of date. Use the name of the field (fromdate) in your select statement or as a variable in your report.
Good luck !