Everyone has given really good advice. Its not something that can be taught in a short amount of time so make sure you set aside a day or at least a few hours. Once you do get the horse caught take him to a smaller arena or round pen and practice taking off the halter, approch, put the halter on throw the rope over him and rub him with halter and lead rope a bunch. My mare was like that when I first got her, I started going out with just a lead rope doing a zig zag toward her not straight on, if she acted like she would move away I moved away before she did. When I could get close enough I just used the lead rope up from under the neck and pet her. Then let her go. Over and over and over again. I think a previous owner must have hit her a lot with a rope because she was scared of it. Had to do a lot of rope rubbing with her
It helps if you can go out in the pasture and once you get him caught just do some grooming and lovey time then let him go, no work. I also bang on the metal gate every time I feed so they always come whenever I bang on the gate. I used to whistle but not everyone can whistle so decided a metal gate noise was better. Good luck and I'm sure you will get it. It just takes time and patience.