Current User is found by using the CurrentUser method:

debug.print "The current  user is: " & CurrentUser

Users can belong to more than one group - here's a function (albeit not very
useful except for display purposes) that gets a list of all the groups to
which a particular user belongs:

Public Function UserGroups(strUser As String)
   Dim ws As dao.Workspace
   Dim strUserName As String
   Dim strUserGroups As String
   Dim usr As dao.User
   Dim inti As Integer
   Dim grp As dao.Group
   Set ws = DBEngine.Workspaces(0)
   For Each grp In ws.Groups
       For inti = 0 To grp.Users.count - 1
           If grp.Users(inti).Name = strUser Then
               strUserGroups = strUserGroups & grp.Name & ", "
           End If
       Next inti
   Next grp
   UserGroups = Left(strUserGroups, Len(strUserGroups) - 2)
   Set grp = Nothing
   Set ws = Nothing
End Function

More often, we want to know whether a user is in a particular group. A
UserInGroup function will give this information. The UserInGroup function
can be done a couple of ways  the first involves 2 functions - one to ensure
that the group exists, then if it does exist, the  second to determine
whether the user is in the group. This method is a bit more reliable than
the second I'll show later:

Public Function UserInGroup(strUser As String, _
 strGroup As String) As Boolean
   Dim ws As dao.Workspace
   Dim strUserName As String
   Dim usr As dao.User
   Dim inti As Integer
   Dim fUserInGroup As Boolean
   Set ws = DBEngine.Workspaces(0)
   If GroupExists(strGroup) Then
       For inti = 0 To ws.Groups(strGroup).Users.count - 1
           If ws.Groups(strGroup).Users(inti).Name = strUser Then
               fIsUserInGroup = True
           End If
       Next inti
   End If
   UserInGroup = fUserInGroup
   set ws=nothing
End Function

Public Function GroupExists(strGroup) As Boolean
   Dim ws As dao.Workspace
   Dim strUserName As String
   Dim usr As dao.User
   Dim inti As Integer
   Dim fGroupExists As Boolean
   Set ws = DBEngine.Workspaces(0)
   For inti = 0 To ws.Groups.count - 1
       If ws.Groups(inti).Name = strGroup Then
           fGroupExists = True
       End If
   Next inti
   GroupExists = fGroupExists
   set ws=nothing
End Function

Here's the one function method - note that it does not differentiate the
error that occurs if marked line fails.

Function UserInGroup(strUser As String, _
 strGroup As String) As Boolean
   Dim ws As Workspace
   Dim strUserName As String
   Set ws = DBEngine.Workspaces(0)
   On Error Resume Next
   ' if this normally line fails then the user is not in the group
   ' but it could fail due to some other error condition so
   ' this method might be considered a bit sloppy
   strUserName = ws.Groups(strGroup).Users(strUser).Name
   UserInGroup = (Err = 0)
End Function