In stories, most of the text is in past tense because it's sort of a recount of what happened by the narrator. The reason you'd see present tense if it was in dialogue, what the characters say, since the story is happening in their present. It's sort of confusing if you haven't grown up with it, but the main rule is to stick with past tense in your actual writing, and use present tense when having your characters speak (unless they're recalling something, etc).