If I understand correctly, this is how you would do it:

1) Create two parameter fields called: Start Date and End Date

2) Open the formula expert and go to Selection Fromulas\Record Selection. This can be found in the 'workshop tree' on the left side of the formula expert.

3) Enter the following code (replace the bolded parts with the appropriate field from your database):

{transactionsummary.date_tm} >= {?Start Date and Time}
 and
{transactionsummary.date_tm} <= {?End Date and Time}

Once you save, you will be able to enter you desired date range. Any data that does not fall within this range will be filtered automatically.