Creation: Why and How.
The Divine Function for Which the Natural World Has Been Created provides a brief overview of the basis of creation, and its implications.
Creation is an in-depth review, by a noted scholar of the Writings, of the full scope of how creation was done, from how God finited some of His infinity to provide the substance of creation to the relationship of the spiritual and natural suns.
The Divine Proceeding to Create reviews this huge process from a somewhat different perspective.
The World of Appearances provides a few initial examples of the implications of living in this world, where spiritual reality is hidden behind the physical reality we perceive.