Hmmm, here is what I would do to just track visits.
Create a table that stores UserName and DateVisited.
Then on your main form that opens when you open the database, on the On Load or On Open event, capture:
Dim stUser As String
Dim dtDate As Date
stUser = CurrentUser
dtDate = Now()
Then pass them to the table
In this what you want? Or do you want to know who is creating and modifying records in your database?