Fill a wide mouth gallon jar with cider and sweetener, if using. Leave two or three inches of headspace. Cover the jar with cheesecloth or a kitchen towel and secure with a rubber band.
Put the jar in a dark and quiet corner, and give it a vigorous stir with a clean wooden spoon every day. You may want to set the jar on a pan or something to catch any overflow.
Once it gets to this point that means the fermentation is going good and it’s time to transfer it into a jug with an airlock. This will keep any unwanted yeasts out.
Then put it back in the dark corner and let it ferment away! Soon you will see lots of bubbles in the jug, if you didn’t already, and the airlock should be bubbling away as well.
Once the bubbles subside, which took about a week or so, then it is time to bottle the cider. I usually use flip top grolsh style bottles.