Robot arm arduino+adafruit motorshield + firmata + VB,run dc motor in reverse?

Well, I am using StandardFirmata.. so the same code that comes default with Arduino.. there is no code, only the test app which moves them only in one direction, which is why I have my question, How do I go about making them run in reverse? I've read on another forum I need to edit something in either the default Arduino StandardFirmata sketch or FirmataVB order to make it run both forward and backwards, this is where I don't know where to start

Sorry if it's confusing, it's hard to explain