A word of caution - do not cut them too short, or into the rabbit's blood line in the nail. That is called the "Quick" or "Quick Line". You must only trim the area below that, away from your rabbits foot. Most of all, read this informative article and learn how to trim a rabbit's nails before you try the first time!
Lastly, if you do not feel comfortable doing this, most Vet's can trim your bunny's nails and only charge a minimal fee. It is a great alternative!
The Rabbit Haven provides the following advice on how to trim a rabbit's nails:
"How to trim bunny nails: Place the bunny in a comfortable position where you can easily reach their feet. We tend to do nail trims with the rabbit laying on our laps with feet up towards us, or having the rabbit in a standing potion on a table where the rabbit is comfortable and we can pick up one foot at a time to trim the nails. A third choice is to use a cuddle approach/hold, where the rabbit is cradled ion one arm as we trim the nails. Some people also use a towel to wrap their rabbit to keep bunny secure. Then they bring out one foot at a time to trim.