A Helpful Method
Dogs have limited vocabulary. Unless and until they have had exposure to a given word or phrase, they will not understand anything. If you continue hundred of words to your pet every time he eliminates, he will not understand anything and will eliminate whenever and wherever he likes. But if you continue to speak a single word every time he eliminates, and you say the word for long period, it is sure that the day will eventually come when your dog will eliminate simply by saying those words to him.
Teaching your pet to eliminate on command is a great idea as you need to tell him to do it here or do it there, which is utmost required when you are travelling or if he gets shut inside a closed room for some time where it is not possible for him to go outside. If your aim is to train your dog to eliminate on command, then tell him certain words or phrase every time .After a few weeks or months, you will find that he will obey your words and eliminate timely. Then take him to the spot and command him to eliminate by using those words. As soon as he eliminates, praise him.