Well, this should be in the Rabbits section, for starters.
This site is great for learning how to take care of your rabbit:
http://www.rabbit.org/
It teaches basics like what to feed your rabbit, where to keep it (in the house!), different toys you can give it, understanding it's behavior, and health information such as finding a vet and a few articles on health problems.
As for getting your brother to take better care of his rabbit, there's not much we can do for that. You could get your parents to learn more about rabbits so they can make sure your brother is doing things right. Or you could take care of the rabbit yourself if you are concerned about it's care. But all we can do here is chat online, and that doesn't do anything to change the way your brother acts.