Your Shard grants you access to a game-like system to manage your power(s). By default, you have access to a basic system which includes attributes and the ability to grow by gaining experience. You gain experience by completing quests or defeating enemies (does not need to involve killing them) and can increase your attributes by training. How the system works in details depends on the Shard, two people with this power can have systems that work differently.
All other powers you select interface through this one and unlock their ability to grow. As you use them, your powers will grow in strength and will unlock new aspects.
Your growth potential is not unlimited, however. Your Shard can only support a certain amount of total progression. This limit will be communicated to you.