Rabbits will need their nails clipped every few months or whenever you notice they are getting too long. For nail clippers, you can get the kind that are for dogs or cats. Human nail clippers work really well for the nails on the front paws, but the nails on the back feet may not fit far enough into the clipper on some rabbits - so it may be a good idea to have a pair of dog or cat clippers as well.
First turn your rabbit over in whatever way is comfortable (you can hold him on your lap or turn him over on a table, like you would do for showmanship) and use your free hand to push the center of the paw to flex out the nails. Rabbits have 5 nails on each paw in the front, and 4 on each paw in the back. Clip off the tips of each nail but be careful not to clip past the red part of the nail because then it will bleed. If you accidently clip past the bloodline and it starts to bleed, you can put cornstarch on it and that will stop the bleeding. If your rabbit has dark colored nails and you can't see the bloodline, you're pretty much safe if you just cut off the very tips.
If your rabbit doesn't feel calm turned over on his back you can try clipping them when he's in his cage - that is if his rabbit pen is elevated off the ground and has a wire bottom. Then when he's sitting there, sleeping you can clip them because they will be sticking through the wire. lol Otherwise if this dosen't work you can try sitting him on a table and clipping them when the rabbit is sitting down, trying to pick up each paw and clip the nails that way. It also may be good to have someone else there to help you.