I've personally updated the firmware only in Pioneer burners, but the process should be similar in other manufacturers' drives. First you download the correct file for your drive from the manufacturer's web site. Then you make sure you close any antivirus or other software running in the background on your machine. Then follow the instructions regarding unstuffing, unzipping and running the update. Usually you just run the software, and everything else happens automatically.
Senior Editor/DVD Author
New York City