I usually made five gallons of Root Beer at a time and followed the recipe on the Hires Root Beer Extract, which if I remember correctly was something like one bottle of extract, five pounds of cane sugar, five gallons of water, one vial of champagne yeast, bottled in champagne bottles and 2-4 weeks to do it's thing.
DO NOT let it ferment beyond a month or two at the most before consumed unless you want to walk into a wall. I forgot one bottle for over six months...WOW was that a surprise!

