Once it's moist you're ready to plant. Choose compatible plants that require about the same amount of sunlight. Almost anything will grow in a bag garden so pick anything you like. The outer rim should be planted with plants that are full and leafy to camouflage the plastic as they grow. When you're finished you have a colorful movable flower garden.
Herbs grow in a bag too.
Use the same technique concentrating the taller herbs in a the middle and low full growing herbs around the edges. Bag gardening is ideal for growing seedlings too. Just cut slits in the bag to make rows then sprinkle seeds into soil mix. The only maintenance a bag garden needs is an occasional dose of liquid fertilizer to provide food for the plants. Beyond that, it's pretty much plant, go and grow.