The amount of light your Kokedamas can tolerate depends on the plant you have. However, in general, your plants will like bright indirect light. Unless your kokedama is a succulent, keep it out of direct sunlight.
Place into a container of room temperature water about a quarter of the way up the ball. Let soak for 15 minuets. Remove and give a little squeeze to release excess water, then place the ball on a waterproof surface. Frequency depends on the plant and its environment but typically every 7-10 days will do the trick. If your moss ball is lightweight and firm, it’s a good indication that it needs water. Keep in mind, that every plant is different. Some like to dry out while others prefer to stay moist.