You will need:
Mason jar (or any other glass jar with or without lid)
Little stones or sand (coloured or natural)
Little plants (succulent plants work quite well because they need little care, but give it a try with other ones. I love to hear what you create!)
Little dolls, toys, houses or other stuff to make it look like a garden (did not do this yet, have to make them first :) )
Make sure your faery garden won't be too wet (or too dry) because it can ruin your whole garden, especially when you close the lid.
See here my first humble attempt:
Lots of love,