Dogs bark because of different reasons. How often they bark mostly depends on a dog breed.
There are dog breeds that tend to bark more than others. But all the dogs without exceptions have this ability to express the feelings with the help of barking. In order to teach a dog to bark at your command, you need to find a motivation, which can inspire your dog. 
This may be delicious food, or possibility to have a pleasant walk together with the owner. If a dog likes tasty food, show it a treat and give a command “Bark!”. When the dog barks, give it the treat. Several training lessons are enough to make the association work perfectly. If a dog likes walking more, you can pretend that you are getting ready for a walk. Get dressed and take a dog lead.
Having come up to the door, go out without the dog. Your pet will be very disappointed. Then you should turn back to the dog and command “Bark!”. The dog will surely bark after the previous disappointment. So we just need to open the door and praise the pet. In this case the association will appear as quickly as in case with food. Of course, there are many other examples except of these. The main thing is to find a motivation which is the most suitable for your dog, and to use it giving a command to bark.
After successful training of all these commands Sit, Down, Place, Come, Go Out, Fetch, Heel, Jump, and Bark we have a well-bred and obedient dog, that is ready to higher level of training and mastering useful skills. If your pet belongs to toy dogs, you may stop dog training at this stage and enjoy the results of your work, which have given you a well-bred and obedient dog.
The decision about further dog training depends on your free time, dog’s age and breed, and also of what you are willing to achieve. Anyway, you should repeat already mastered exercises every day for the dog not to forget the skills. Remember, that training should be pleasant for everyone, who takes part in this process. That’s why do not work if you or your dog is tired, stressed, or nervous. Every moment of dog training should be full of harmony and joy of communication with each other.
Canine Experts’ Advice
“Bark!” command isn’t a basic command, but it may be useful in many situations. Dog’s ability to bark is considered as a way of communication with the owner. For example, a dog wants to draw owner’s attention to some event or person. Or dog’s owner may use barking as a definite signal.
The majority of dog owners want to train their pet “Bark!” command for a general development, as a dog barking at the command always looks very serious, which is funny and cute.
For training “Bark!” command you will need:
It’s better to teach a dog this command after having trained basic commands. Some dog breeds, that tend to excessive barking love this command. On the other way, silent dogs pronounce their first “bark” at the command very unwillingly. Important is to show persistence, and then you will surely succeed.
This dog command training should be done on a dog lead. It is necessary, because a dog may be distracted and may run away from the owner. Mostly what for you need a dog lead is to hold and control a dog.
1-st Way to Train a Dog “Bark” Command
Choose an object, which arouses dog’s interest. It may be a treat, a stick for fetching, or a favourite toy. A trainer gives this object to a dog to smell. When it gets interested, a trainer lifts this thing over dog’s head. A dog sees it, but cannot reach, because the trainer steps on the dog lead not letting the pet jump. The trainer points at the toy or treat and says “Bark!”. The dog is excited as it cannot reach the thing. 
As a rule, a dog start to bark from disappointment and irritation. When it happens, the trainer immediately gives the training object to the dog. Sometimes the situation is difficult, because a dog isn’t interested with anything. It looks at a treat or ball without any desire to get it. You will have to arm yourself with patience and choose another training method for such a dog.
2-nd Way to Train a Dog “Bark” Command
In this training method a dog should bark because of irritation, not because of interest. In such a case we need a helper who will tease a dog with the gestures, making sharp movement in front of the dog. Usually, even a calm dog loses temper and barks.
You need to repeat the command “Bark!” while the helper’s movements. When the dog barks, it gets a treat. Sometimes dogs quickly learn this command, but then they cannot be calm after it and make noise for a long time displeasing the owner.
That’s why if you decided to teach a dog “Bark!” command, do not forget about “Stop!” command. It will help you to stop your dog’s barking at the command. Some owners don’t limit themselves to this command, and train a dog inflections of a human colloquial speech. For example, at the command “Speak!” a dog starts to utter sounds similar to human speech.
As a conclusion, dog are similar to people, as there are talkers and silent individuals among dogs too. You can train silent dogs to bark, but you will need more persistence and time for it. There are dog breeds, that don’t bark at all, such as basenji. Probably it’s better to teach these dogs other commands, than to make experiments with their vocal cords.
Usefull equipment for dog training:
