EV training is really only necessary for when you want to do competitive battles against other players. If you're only going to be playing through the game, then you don't need to worry about it.
Still, to help you out, there's the 4th Generation FAQ thread, which has a post detailing EV training.
When you're ready to try competitive battling, the Competitive Battling Center will be the place to go. Following the rules there and reading through the Resource thread and Gude thread will give you the information you'll need to create your own thread for the Pokemon team you decide to battle with. The members in CBC will give you advice on how to improve your team, like their natures, EV spread, attacks, or hold items.
Hope this helps!