how to release powder from a height

Hello,
I am trying to run a simulation where particles released freely from a height of 700 µm, due to gravitational and contact forces, these released powders freely deposited into the box and formed a powder bed. A roller is then applied to spread a 50 µm high layer of metal particles.
Can anyone share a code for that ? With which tutorials I can start or modify it or which command I should use ?
I am actually a total beginner. I would be glad if anyone can help through with the steps involved in the simulation.
thnx.