Why do you want your dog to bark? Just for the purpose it is cute to have on command or you want to stop her from barking so if you put it on command she will only do when you say or for a protective reason to scare others off?

The reason could really change the way you train for them to speak.. that is why I ask.. the two suggestions already given work great for just the purpose of barking on command but if you want the dog to scare people away you will need to use a different method.. so let me know if you need that other method..

I have used it already to train my dog to speak to scare people away from myself/my house and my car but yet for as viscous as she looks when she does it she would most likely pee her pants it they just jumped at her and said boo..lol