The plants in your arrangement are staged in their individual nursery pots so that you can easily water each one based on its specific needs. Ferns prefer to stay moist, while orchids, African violets, and most foliage plants like to dry out between waterings.
Check your arrangement weekly by lifting up the moss around each plant and feeling the top of the soil. Water carefully to ensure that the soil is saturated but there isn't too much water standing in the bottom of the container.
Your arrangement will be happiest living in a bright spot that doesn't receive too much direct sunlight. It can also live on a covered porch, but you may need to check it for water more frequently in the summer and bring it inside in the winter.
You do not need to worry about repotting the plants in the arrangement; they should be happy to live in their nursery pots for at least a year as long as they are getting the light and water that they need.