Question

how oracle bones were used during the Shang dynasty?

Answer 1

Oracle Bones was the shoulder blades of oxen/plastrons of turtles which were used in the Shang Dynasty of China (1600-1046) for Heavenly bliss.

Astrologists would carve (later, paint) symbols on the bones of the ox or the turtle shell apply a hot poker/fire till the bone or shell cracked and then interpret the direction of crack through their drawing to predict the future.  

Those symbols later became words and a recognizable Chinese script evolved from this practice