Display a form once Excel executed

This code will let the designed Form to appear in the screen once the Excel file executed.
To set this go to Project Window and double click at ThisWorkbook. Copy below code and change the form name as you want eg. frmReadDir.Show

Private Sub Workbook_Open()

    On Error GoTo error_message

        frmReadDir.Show

    Exit Sub

error_message:

    response = MsgBox("Error " & Err.Number & " " & Err.Description, vbExclamation)

    End

End Sub