Kristin, we need to teach your horse that coming to you, and having a halter and lead rope, feels good. You will need some patience and a bunch of tasty treats.
Begin by simply walking out to the paddock, your body turned to the side in relation to him, with a feed bucket containing a few treats. If he approaches, feed him a treat and then leave. Repeat this until he starts coming up to you as you approach. Now, hide the bucket behind your back and repeat the process. When he is coming reliably, remove the bucket and move the treats to your pocket. Next, put a halter and lead rope around your shoulder when you come out and repeat the process.
Be sure to slowly increase what he needs to “do” to obtain a treat. First, stroke him with the lead rope, then wrap the lead rope around his neck and remove, then open and close the halter, and finally, place the halter on him. Remember to pair the halter and bringing him in with good things—a treat, a good grooming, etc. Soon he will be running to you instead of away!