You need a scoby, after you have that, you make really sweet strong tea add the scoby and let ferment 7-14 days depending on taste. After it has reached your desired level of acidity, you have to bottle it and let it sit one more week to carbonate. I use grolsch-style bottles because they are reusable.
Growing a SCOBY
Buy a bottle of kombucha
pour the bottle in a quart mason jar
cover with a clean wash cloth and rubber-band it so it wont fall off.
place in a cool dark place until the scoby gets to be about 1/2" thick.
now its ready to use
I make mine about a gallon at a time, if you want to add other herbs to the tea you can, but you must always use the same amount of black tea because that's were the SCOBY gets its nutrients from.
What you will need:
12-14 teabags per gallon of water
4 cups of sugar per gallon of water
a big pot to boil the water in
a glass jar that holds a Gallon + of water
first you boil the water hard for a few minutes, then you pour it into the glass jar (I always have the jar 1/4 full of room temp water so I dont bust the big jar) only fill the jar 3/4 of the way
add the sugar and stir
add the tea bags and let steep until the water in the jar is less than 90 deg.
now that the strong sweet tea is cool, add the scoby and some of the old kombucha (it acidifies the water making it more suitable for the bacteria and yeast)
cover with a piece of cloth and let it sit in a cool, dark place for 7 days, taste it if you want a stronger flavor let it sit more.
now to carbonate it, pour the kombucha into grolsch bottles and close the top, let those sit about a week then you can refrigerate and enjoy
You can adjust the sugar, but i would wait until after you try it, because the yeast uses a lot of it up.
hope that helps