You need to start out with something simple for both him and yourself first. I had to do this with one of my buns who had really poor litter habits when out in his play area. And now I’m starting on getting my three little ones into a carrier with it.
You really should check out the site RabbitPam listed, it’s awesome and the first free chapter really helped quite a bit.
What specifically do you want to teach him to do first? It’s easier to figure out a process if we know what you’re trying to achieve with your bun. And also small steps with him! You want to teach him what you want him to do only through reward and he’ll catch on a lot quicker if your actions are easier for him to pick up on. Like for litter training with my bun, during a session I’d say Fluery, Litter! And nudge him into the box. He’d get a treat. He quickly caught on. And I would do small sessions early on to make sure you don’t frustrated if it’s difficult at first and so he doesn’t run out of attention span. I typically did 5 minute sessions twice a day with my boy and he caught on within a week of what I wanted him to do. Now as soon as he comes out of his house he knows to hop in his box and go to the bathroom before running around. It makes for a much happier momma and bunny!
Rabbits really do enjoy learning and I’m glad to hear you’re using this means to teach your bunny things and get closer to him!