Usually, live lobsters are sold with rubberbands around their claws. You'll want to leave them in place until the lobster is cooked (unless you want to find out what a lobster can do with his crusher claw). Once you've twisted the lobster's claws away from its body, however, you can remove the rubberbands with complete confidence. In a restaurant, the rubberbands will probably be removed before your lobster is served.
Using a lobster cracker or nutcracker, your next task is to crack open the claw and claw pieces.