You can find all those informations by making a search through this website. The House Rabbit Society website also has a lot of good articles on the subject.
If you've got a male, picking a female is the best - 2 males is the worst combination possible. But DO NOT attempt to put them together until both are neutered/spayed. In my experience neutered male WILL try to mount an intact female and he can be seriously injured for trying if the girl isn't agreeable (don't think because the female is younger or more tiny, she can't seriously hurt your rabbit - I've seen several cases of a girl butchering the male's genitalia with a good bite when he tried to harass her). Also, even if it goes well it means you will have to separate them when rabbit n°2 will get spayed which will result in the need to reintroduce the 2 rabbits from scratch (and introductions can be easy or very hard depending on the rabbits).
The best is either to take a young female and keep her in a separate area until she's spayed or to get a spayed female from a rescue (some people also sometimes give away adult spayed rabbits they can't / don't want to keep anymore).
