Pokemon Firered EV training... I'm a noob?

Ok. This is my first attempt to EV train a pokemon. I have not beaten the Elite 4 yet, but I am trying to EV train my Aerodactyl for attack. It has a docile nature, which, i think, is neutral. I have an idea of how to EV train, but I'm not completely sure how to yet. From what I underestand, you fight certain types of pokemon, regardless of trainer battle or wild pokemon battle, that will give certain amounts of EVs to a certain stat. When you level up, you will gain more stat points in that area. Is that right? I just want to make sure that you can train against other NPC trainer pokemon and that I am not wasting my time by fighting this biker with a machop and machamp over and over. Can you please explain how to EV train or let me know if my understanding is correct? I also want to know what the best place to train for attack is. Thank you