Kefir is easier and quicker to make than kombucha, there is no caffeine and maybe less sugar. Probably the best intro to fermented drinks!
Combine ginger + sugar + water in a quart jar. Let it sit for 3-7 days, covered but open, at room temp. Will stary to bubble. These are your live ginger yeasties, or ginger bug.
Boil a big batch of ginger tea (more ginger + sugar + water). Cool to <100F, add ginger bug. Strain. Bottle in plastic bottles (glass explodes on me sometimes). Ready in 3-7 days. Gets boozy if you leave it out longer.
Add a little citric acid and/or lemon juice at tea step to give it a little acid to counteract the funk.
glass, plastic, etc.. Buy some swingtop beer and you'll get the bottles for free. screwon - be it glass or plastic - also work.
There's also surely 1000 articles and videos on this very topic, but its not important