As to how it works, there are differences of opinion. A popular notion going back to Plotinus is that events in the heavens and on earth run parallel, but this fails to take into account the fact that conjunctions between planets are conjunctions only as sensed from the earth, so sensing on the cellular level seems to play a role. In effect, planets seem to be sensed and used as timers and regulators. Organ A relies on planet A, and organ B on planet B, so if the planets are in conjunction, organ A also reacts to planet B, and organ B to planet A, and they change their specialization a little. This is now known as trans-differentiation. For instance, I once knew a woman with digestive problems. The remains of food were found to be lodging in sacs in her stomach instead of being passed along the gut, to be excreted. At her birth, the moon (stomach) had combined with Mercury (lungs), so apparently her stomach had become more like a lung in developing alveoli (air sacs).
That is a very large subject. Judith Hill is a good start.
Books are a valuable tool, and not that expensive.