What should I do with a baby rabbit I rescued today?

see if there is an animal rescue in your area. a vet can certainly make a recommendation.

sounds too young to release into the wild.

Either take him to an animal rescue or a vet, or care for him yourself. Don't set him free yet. Some vets actually see wild animals for free, so you could check that out.

While you're looking after him, just leave him in his cage by himself with some straw/hay, or if you don't have any, some newspaper on the bottom and an old rug or something to keep him warm. He will eat carrot, but he's probably just too scared to eat it yet. Just leave him with it and he'll eat. You can peel the carrot with a peeler to make it easier to eat. He would also like lettuce (not too much), broccoli, celery tops, silverbeet, and apple. If you have him for quite a while, get some rabbit food for him, from a pet shop. Put a heavy pot in his cage for water so it doesn't get tipped over, if you don't have a rabbit water bottle.

You might want to just care for him until he's healed, with no risk of infection, and then release him. Rabbits grow pretty fast, so even if you just keep him for a couple of weeks he will probably be big and strong enough to fend for himself in the wild.

You should definitely bring it to a vet or it's eye could get infected and as said above the vet can help/guide you from there.