Sum several tabs

[GCLIFTON]

i am trying to updated this VBA to now sum Column D and c start with D3 AND C3 in each spreadsheet that it opens and place the value in Column L AND M on the Sumarry_1 Tab. Currently it just copies the the second line in each sheet to the summary_1 tab inwhich i would like to keep. So basically we are adding L AND M that is the sum of C3:Last Row AND D3:Last Row

 Sub openfILES()
    Dim sh As Worksheet, wb As Workbook, lr As Long
    Dim Source As String
    Dim StrFile As String
    expPath = Range("B5")       'pull export file path from cell B5
        Set sh = ThisWorkbook.Sheets("Summary_1")
    Source = expPath
    StrFile = Dir(Source & "*.tab*")
    Do While Len(StrFile) > 0
        lr = sh.Cells.Find("*", , xlValues, xlPart, xlByRows, xlPrevious).Row
        If StrFile <> ThisWorkbook.Name Then
            Set wb = Workbooks.Open(Source & StrFile)
            If Application.CountA(wb.Sheets(1).Range("A2:K2")) > 0 Then
                wb.Sheets(1).Range("A2:K2").Copy sh.Cells(lr + 1, 1)
                wb.Close False
            End If
        End If
        StrFile = Dir()
    Loop
  MsgBox "Done!"
End Sub