i use this to log user name ond time of last change, the data is saved to a hidden sheet
hope this is of some help
Private Sub Workbook_Open()
Dim user As Variant
Dim mytime As Date
user = Environ("Username")
mytime = Now
Sheets("Admin").Visible = True
newrow = Sheets("Admin").Cells(1, 1)
Sheets("Admin").Cells(newrow, 1) = user
Sheets("Admin").Cells(newrow, 2) = mytime
Sheets("Plan").Select
Range("A10").Select
Sheets("Admin").Visible = False
End If
End Sub