Oxbow is a good brand of pellets. They sell that at PetSmart. Kaytee is not as good as Oxbow, but it would still be a good choice. You can get Kaytee at PetSmart or Petco, or maybe some discount stores. You need to choose pellets that don’t have any colored bits or seeds mixed in with them – you want pellets only.
Some good veggies to give the rabbit are romaine lettuce, green or red leaf lettuce, parsley, cilantro, and kale. Fruit should be given sparingly, but apple or pear would be good ones to try.
Even if you have a fenced yard, it’s not good to let the rabbit run loose in it. They can dig out under fences and predators can climb over or fly in to attack them. The rabbit could also pick up fleas or ticks or get worms if it eats vegetation where other animals have gone to the bathroom, so it’s much better to keep it inside, even if it has to be in a kennel. Hopefully, the kennel is large enough so that it can hop around.