Bear in mind that if your horses are in any way pushy or excitable, or likely to bite or kick, it’d be safer if he can just help you with the jobs in the yard first. He mustn’t handle them, as this would be unsafe and unfair and won’t build confidence. Over time, he could do more, but always under your supervision. If your horses are kind and easy to manage, then start with the basics. He needs to feel confident with doing small things first. Grooming is an excellent way to start.