First things first- Sex your bunnies to make sure you do in fact have a Buck (male) and a Doe (female). You need to do this around 3 months + in age. If you try to do this when the bunnies are too young, you will have a very difficult time determining who is what. The males sex organ looks round while the females appears as a slit. As they get older, it will become more obvious to detect.
If you are looking to breed rabbits, either for food, for selling, or you just like having bunnies around ...everywhere, then you only need one good buck. Do not get more than one male, and if you do, make sure they are not confined together. Typically one buck does the trick, no pun intended, and have a couple of does, depending on how many bunnies you want to raise. For large scale rabbit raising, 1 buck can handle up to 10 does at a time.
When it comes to breeding, keep the females in separate cages. Do not bring the buck into the females cage when you are ready to mate them. Always bring the female into the bucks cage. The females get frightened and territorial and may fight off the buck if you bring him to her domain. She will do this instinctively to protect her non-existent nest.
Every now and again bring the doe to the bucks cage and let them do their thing and then return the doe back to her cage. Rabbit females ovulate when they have sex, and produce multiple eggs. There is no set cycle like for human females. When the doe is pregnant, she will run away from the buck and not let him mount her. From this point on, start counting. In approximately 30-31 days she will birth her litter.
The ultimate sign of her being pregnant is you see her biting and yanking her own chest fur off to make a nest. You can help her out by giving her fluff from her previous litter, or sheep wool, or scrap soft fabric. Hay is a good nest material too, or if you are in a pinch, dried out pine needles. You don't need to help her build, just pile all of that material into her cage and she will set herself busily to work. It's pretty amazing actually to watch.
Make sure you are are feeding your pregnant doe enough. If she is not eating proper amounts of food some of the babies may die inside her and she will abort them. The last week let her eat as much as she is willing to ingest. If a doe does not receive nourishing food or enough of it, she may yield a very small litter.
About 5 days before she gives birth (called "Kindling") make sure that you briefly check on her to keep water full and to feed. She is a nervous momma at this point, and you don't want her to injure herself or her litter if she feels like her space is being invaded.
When she starts to give birth, check periodically on her to make sure that she is using the nesting box. First time mothers are often very excitable and may give birth outside, where the newborns may die from cold. If you see that some of the babies are outside, take some Vicks Vapor Rub, and put a dab on the mothers nose. Take some gloves and pick up the babies and return them to the nest. This is very important because if the mother smells you on her litter she will abandon them.
It does happen that because of nervousness, or lack of food, that the mother may cannibalize her babies. Give her at least 1-2 more chances to give a good litter, and if not she should be used for eating or just sell her.
Around Day 10 after birth, the baby bunnies are starting to open their eyes and become much more active. You do not need to supply any additional food for the babies, moms milk is still suffice at this age.
Around Day 21, the baby bunnies can be fed other food besides moms milk. First supplement gradually some milk soaked bread, these young ones have a very delicate digestive system. So all changes must be a little bit at a time. If you are feeding them grains, make sure they are well crushed and husks removed. Leafy hay and grain are good for them at this age.
Any bunnies from this new litter that you don't want kept for breeding should be butchered by at least 13 weeks of age, after that you are just wasting money on feed and it is no longer cost effective to keep the animal.