i thought this thread is about MS Access?
if it is, you need FileDialog so user can pick (or create new folder).
on VBA, you need to add Reference to Microsoft Office X.XX Object Library:
Public Function DirPicker(Optional ByVal strWindowTitle As String = "Select the folder where Backend is located") As String
Dim fd As Office.FileDialog
Set fd = Application.FileDialog(msoFileDialogFolderPicker)
fd.Title = strWindowTitle
If fd.Show = -1 Then
DirPicker = fd.SelectedItems(1)
Else
DirPicker = vbNullString
End If
Set fd = Nothing
End Function