Discipline and exercise..........and a crate.
Group classes are not the best - too many distractions.. Either hire someone for some one on one training or do it yourself.
Make him sit and lie down before you give him anything - a toy, his food, etc. Once he's mastered that, teach him the down-stay initially using his food as a reward.
That dog needs hours of exercise, but nothing too hard on his growing joints. Remember, a tired dog is a well behaved dog and a well behaved dog does what you tell him to do when YOU want, and does not test you.
Flirt poles work go, as do lunge whips, walks or throwing a ball in the yard. Fetch is a good time to teach him drop it, leave it was well as down-stay. Walks are good, as long as he heels and that YOU lead the way. Once you've properly leashed trained him, you'll be surprised quickly the rest of the obedience falls in to place.
When walking, make him sit and stay when you stop, before you cross the street, etc. Remember, you are the boss. He gets love, food and permission to do things when YOU decide.
When he's older and his joints are done forming, buy a walky-dog or a bike tow leash and bike with him. Bully breeds have boundless energy that needs to be used or problems can arise.
When he shows you that he can be trusted and is well behaved, you can put the crate in the attic. Until then, he goes in it when you are not able to supervise him.
We have a 15 year old staffy bull and a 2 year old patterdale.