First you have to have a way of identifying what's changed.
Possibilities include:
1) Compare the database as it is now with a copy of it as it was before.
Link the corresponding tables and use queries to find non-matching
records.
2) Add a pair of date/time fields [Created] and [Modified] to each
table. Set the default value of Created to Now() to get a timestamp when
the record is created; use code in the BeforeUpdate event of your forms
to update Modified and get a timestamp when the record is modified. You
also have to ensure that users can only access the data via forms. Then
you can just query for records that were added or modified in the period
of interest.
