My status: Coming from AutoCad, I'm now taking my first steps in Solidworks.

My task:

#1 To model an "high-cube inter-modal refrigerated container" (aka "ISO container", "shipping container", "reefer"), without the actual cooling mechanism.

(I've got detailed drawings for Hapag-Lloyd containers, and am acquiring Maersk container drawings also)

#2 Then make some cuts into the container for door and windows openings

(I've got the approved drawings from the architect)

#3 Finally simulate the dead and live loads, for the local municipal building authorities.

Now, as I like to eat the elephant in very small bites, I started by making a mockup object to test in Solidworks: a simple box and cut-extrude to make it hollow from the side. I then applied External Load (Force) on top, and my question is: Should I then select "Fixture" of some sort to the bottom of the box, to represent the ground?