Just watch the clips and follow along. This is the most time consuming part of building a tank.
Turrets
Turret entities are the primary method for aiming things on your vehicle.
Most tanks have a vertical turret ring parented to a horizontal turret ring parented to a baseplate. Armor is then parented onto the relevant joint.
Guns
Guns can be used to damage other vehicles.
We will make them shoot in another tutorial. For now they are placeholders.