For halter, if you could take lessons from someone with a trained horse, you'll learn a lot. I showed it for the first time last year, and it's definitely not as easy as it looks. There are a lot of little cues on those horses, and if you don't hit them just right, the stand up looks bad. It's hard to explain, but if you can set up a trained horse a few times, you'll get an idea of it. Just using treats to get them to lift their necks/heads isn't enough at all. You actually start by teaching them to set their hind legs, then the fronts, and you end at the neck. You have to get the foundation first. With the neck, it has to come up out of their withers, not just straight out. They have to be set back on the hind end (which is why you start by teaching them that first, lock their legs, and then learn to reach UP and then OUT with their neck.
As far as the riding, that should come on its own. Forcing a frame isn't a good idea, and you can tell it when you see them show. Once they start learning self carriage, you'll see that neck really develop as it should.
ETA: I provide videos, so here's a video of me showing halter at Regionals last year. I'm the last to show here. My mare ended up 3rd somehow, which I'm still irritated about. BUT, it was redeemed when she was third at Canadian Nationals (out of several more than 3...lol). That's much more important than a Regional class..lol.