I am newbie in simulation, be patient please...

I have to check wall thickness of some kind of water tank.

This will be some large barell, diameter 2meters, and 2 meters high.

Material - aluminum.

Tank will be filled (fully) by oil, c.a. 9kg/dm3.

Can somebody explain me step by step how to simulate behavior of walls of barrells? How to check how thick will be walls?