There are many methods of reviving dried chilies.  Perhaps the easiest and fastest is to put the chilies in a sauce pan with enough water to cover amply.  Bring the water to a simmer, cover and turn off the heat.  Let sit for about 15 minutes, or until the chili is soft and supple.

Also adding boiling water to a bowl of dried chilies to cover for ten minutes will do the trick.

Keep in mind that touching hot chilies will lead to a painful experience with an eye, nose or mouth if you do not use gloves or a plastic baggie to handle chilies by hand.