In order to make kombucha, you need a starter (also known as a mother or a SCOBY (Symbiotic Colony Of Bacteria and Yeast), you need some black and/or green tea, and you need some sugar.
If you can get a starter from a friend or from craigslist, then follow these straightforward instructions to make your own batch of kombucha. Later, if you want to get fancy, you can try some of these other methods.
If you can't get a starter, but you can buy some raw, plain kombucha at a store, you can probably grow your own starter, and proceed from there. See this excellent series of posts on kombuchafuel. I've meant to run this experiment myself, and I still may try it, but I'm glad that kombuchafuel has done it.
In fact, the kombuchafuel site may answer all of your questions about kombucha, even the ones you didn't know you had. Awesome website!
A few more thoughts:
- Save the empty bottles from whatever kombucha you buy. You can use them for bottling your own home-made kombucha.
- If you want to try using things other than black and/or green tea as a base, I'd recommend setting aside some of your original starter, in case things go awry.
- If you want reproducibility, take notes on amounts of tea, water, and sugar, ambient temperature, etc. Then when you make that "perfect batch", you'll have a better chance of repeating it.