The tannin isn't really necessary, but the apple varieties that are traditional for cider-making contain more tannin than most other varieties, so I usually add a bit, without really bothering to measure.
Get the tannin and the yeast and the hardware from a brewing supply store. (I you don't have one near you, there are several on the internet.) If you've never tried anything like this before, you may also want to get a beginner's book on making beer. (Make sure to ignore all the hard parts, since they aren't needed for making cider.) You can buy bottles at the brewing store, too, or you can just save old beer bottles. If you do the latter, remember not to use the twist-off kind, as the pressure of fermentation tends to blow the caps off them.
Put 5 gallons of juice into your fermenting bucket, add the tannin and the yeast, stir, and seal. Let it ferment at room temperature for a week or so until it stops bubbling. Add the rest of the juice to supply carbonation. Bottle. It'll be ready to drink in a week or two. Serve cold.
If you try this recipe or have any questions, write to me at