how do you get the folder names from a directory

I am trying just to get the colder names from a directory after i search to see if a file exists or not.

my current code is as follows:

 Private Sub file_search_Click(sender As System.Object, e As System.EventArgs) Handles file_search.Click
        Dim search_file As String = "xxxxxxxxx/yyyyyyy/vvvvvvv/*/*/*.sig"

        If System.IO.File.Exists(search_file) = False Then


            For Each missing_file In search_file

                txt_PS_Progress.Text += vbCrLf + missing_file

            Next


        End If
    End Sub

in the search_file as string i had to block out the path with xxx yyy vvv .
the * are muliple folders in the above directories that must be searched for the missing .sig file

all i want to return is the folder name from the search that is missing the file with the .sig


thanks in advance