Go to a glass shop and pay the $$$ which usually isn't all that unreasonable . considering that if you attempt it yourself, you are most likely going to break it. Those guys have the tools and experience and will make it look embarrasingly simple and knock the job out in about 10-15 minutes or so. Some boneyards even have glass installers on the premisis, because nobody really has any business messing with glass unless you are setup for it.
I'm the last person to tell anyone to chicken out on doing anything themself, but glass replacement is one thing best left to those setup to fool with it