Streamlined and simplified dictation
Chris Hoffman gives a quick run through of how to use the Dictation feature on Mac. You'll need to be running at least Mavericks (OS 10.9) to take advantage of this. The article also gives a list of all the dictation commands you need to know.
"The Mac Voice Dictation feature is streamlined and simplified. It's easy to start using without a long training process and will feel familiar to people who've used voice dictation on smartphones and tablets. In fact, it's extremely similar to the voice dictation feature on Apple's iOS."