Capture User-Selected Filters for Further Use

Hello!  I am using a custom SSRS report for forecasting (SQL, not Fetch).  I have enabled prefiltering by using the CRMAF_ prefix, allowing system users to select beginning and ending dates (either specific dates or ranges like "This Month") for the forecast period he/she wishes to view.  I'd like to store the user's selection of beginning and ending dates in parameters on the report for use in a later query on the same report.  Does anyone know how to do this?

If I'm not explaining this well, please let me know.

Thanks!

TSW