Yes, I agree with the others. Choke collars are a no no with puppies, and I believe they shouldn't be used at all.

Boxers are awesome dogs, they are highly trainable and have a strong urge to please you. However, if not trained, they can easily become uncontrollable with their size and strength. Better start continuous training now because the older he will get the harder it will be to control him.

I agree with Karen, go to your local library and get some dog training books. I believe positive training (no punishments, using your dog's natural sense to please you) works best, instead of negative training (punishing physically or verbally when something wrong is done).
Both can work, but they both can be done wrong. There are plenty of internet sources you can find.

Boxers need plenty of EXERCISE! I'm sure you know this by now. They're are an obedient breed and they pick things up easily. However, they remain very puppy like and continue to have a short attention span. Use lots and lots of treats and keep training sessions short. It'll take some time but with training boxers make great pets. (My boxer is pictured in my sig at 6 months old. He's now 2 years )

Good luck!