first buy a gallon bottle of organic unfiltered apple juice or any natural apple juice and a can of frozen apple juice concentrate(any flavor). also buy a pack of dried ale yeast and a rubber stopper(number 8 works for the apple bottles i use) and a bubbler/airlock from a homebrew shop (alternately you could use a balloon on the top of the bottle but let the air out of it if it looks like it will pop). then pour out about 2 cups of juice, and add the thawed concentrate to the bottle. you need to leave some air space at the top of the bottle or the cider will ferment out of the bubbler. shake the bottle up good then add the dried yeast. place the bubbler and stopper on the top and set it in a room cooler than 80 degrees and cover it with a dark t-shirt or towel and let it ferment for 5 -8 days. it will be a little rough around the edges but it's still good. i like to add a little unfermented juice when i drink it to sweeten it a bit. just poor into a glass or into another bottle and drink it.
the stronger you make the cider(buy adding more sugar or sugar sources) the longer it takes to ferment. you can do this with citrus juice too. this recipe is ultra simple. ideally you should sanitize everything with iodine solution but this will still work if you don't. to make a nicer cider you could rack(siphon with a hose and racking cane) the cider to a second bottle to mellow for a week or two. then you could bottle it with a small amount of sugar to carbonate it in the bottles. that takes a week or 2. that all takes more effort and equipment.