The easiest way to temper is by using a tempering machine, but most home cooks don't have one of those lying around! Chocolate needs to be melted with an indirect heat source. I prefer to use a double-boiler method, because it allows you to develop a keener eye and feel for the difference in appearance and heaviness of chocolate that is 90°F versus 120°F.
Bring a small pot of water to a boil. Turn the flame off, and place the bowl of chocolate over the pot. Allow the chocolate to melt by the steam rising to the bottom of the bowl. Use a candy thermometer to monitor the temperature; however, be sure to stick it in the chocolate without touching the bowl, which can give a false reading. Once the temperature reaches between 115°F to 120°F, quickly remove it from the stove.
Warning! Do not allow even a drop of water to touch the chocolate. Water is chocolate's worst enemy. Even one drop will turn the entire bowl into an unworkable mess. If this happens, use the chocolate for brownies or hot chocolate, but forget about tempering.