These terrariums are very easy and fun to make - you will need some stones (for drainage/airflow), some potting mix, little twigs/branches with moss growing on it, delicate mosses, tiny little ferns - basically any miniature plants. You will be able to find these by visiting your nearest garden centre.
All of the items will need to be layered - stones, potting mix, and then the plants, give them a little water and put them in a nice shady spot.
These mini 'gardens' are great because they don't require a lot of upkeep (just keep them out of the hot sun), and give them a little water so they grow. Perfect for people that live in apartments due to space restrictions. These little gardens would also look great displayed in a round glass bowl - however in this example, I have used a clean household jar which will work well too.