How to log data changes in Access at the table level?
Unfortunately, Microsoft Access doesn't have triggers, or anything even resembling triggers.  Off the top of my head, you have a couple of unappealing choices:


Create DateModified and UserModified columns, and update your code to include these values.  The downside is that you'll only know the last person who updated a record, and won't have a history to look at..
Keep your Access front end, and port your tables over to a SQL Server Express back end.  This way, you'll be able to use triggers (as well as back-up jobs and other nice things).