Hi Olutoba: For static you can use "remote load" if you know the weight and CG location. Create a coordinate system at the CG for easy selection. You can select the interior surfaces of the vessel and choose the reference coordinate system at the CG, and the direction of the weight relative to that coordinate system. Software will distribute the force uniformly on the surfaces. A symbol for the force will show at the CG, and you'll see purple colored leaders extending to the surfaces of the vessel.
Alternatively, you could just apply the standard "force" on the interior vessel face and specify a direction. The software will distribute the load uniformly to the interior faces of the vessel, but the effective location of the force will be at the geometric CG of the selected surfaces.
If it's a vibration problem you're doing, you will have to specify a "remote mass", instead of a force. Hope that helps.
Why not just apply pressure equal to the static head on the lower boundary of the container?