This video shows the process of fermenting apple juice that you can buy for about $3.50 a gallon from Costco.
Please see the Amazon links for products used in the video: https://amzn.to/2KBw7Um
What you need to brew cider:
EC-1118 Champagne yeast – http://amzn.to/2qh5zMm
#10 stopper – http://amzn.to/2qgJGNh
Airlock – http://amzn.to/2rR2FiB
Siphon – http://amzn.to/2rAlvgx
Open the apple juice, dump in the yeast (each packet is good for ~5 gallons, so break it up if you are doing 1 gallon at a time).
Dump out a little juice to have about a 1″ gap, put in the stopper & then the airlock.
When the cider goes clear & stops bubbling, you know it is done. Chill down in the fridge for a few days, then siphon to another container (Keg / Bottles / Etc).
If you are kegging, you need the following:
Complete keg kit – http://amzn.to/2qcFUZh