Narration can come in two forms; one of which is a viewpoint of a character within the story or a person who tells the story as if he/she were speaking to an audience. It all depends on how your story is being portrayed.
'All narrators present their story from one of the following perspectives (called narrative modes): first-person, or third-person limited or omniscient. Generally, a first-person narrator brings greater focus on the feelings, opinions, and perceptions of a particular character in a story, and on how the character views the world and the views of other characters. If the writer's intention is to get inside the world of a character, then it is a good choice, although a third-person limited narrator is an alternative that does not require the writer to reveal all that a first-person character would know. By contrast, a third-person omniscient narrator gives a panoramic view of the world of the story, looking into many characters and into the broader background of a story. A third-person omniscient narrator can tell feelings of every character. For stories in which the context and the views of many characters are important, a third-person narrator is a better choice. However, a third-person narrator does not need to be an omnipresent guide, but instead may merely be the protagonist referring to himself in the third person (also known as third person limited narrator).' from wikipedia.
So the way to implement a narrator to your story is to write as if he/she was actually talking to you in order to tell the story.
