What is the first thing you need to teach a horse before you use any equipment around him?
Trust. If the horse doesn't trust you, he will resist every task you try to accomplish around him. The best way to establish trust is to spend time with him in his corral without asking him to do any task at all. Just be there, doing other things. Cleaning his corral, bringing feed or treats, walking around looking for rocks or other hazards will all help him get to know you. When he's ready, let him smell you and your clothes, touch him on the shoulder, withers, barrel and neck.
Mimic other horses when you are with him. Other horses don't grab on tight when they are trying to establish trust. They touch gently. They let him smell them. Every time you reach toward him, turn your palm down and be still while he smells your hand. Once his curiousity is satisfied, he'll probably allow you to touch his neck or shoulder, but don't try to touch his head until after he trusts you. Pull gently on his mane or push it into a new position. Rub him where he itches and can't reach: chest, neck, belly, back. He'll learn to look forward to your touch. Leave touching his head, legs and rear quarters for last. Only move there when he is relaxed in your presence and with your touch. When he is relaxed and accepts your touch anywhere without worrying, he is ready for further training.