I based the model off of an actuall sub map I found. It has a mess hall, reactor, turbines, bombs, and such. There may be a few small things here and there, but I spent like 20 hours on this thing. I didnt make any new objects, just put some together.
A submarine with more rooms
Load the downloaded file where ever you can find it fastly.
Start the editor and you level.
Start the DB editor
Load all libraries for Entity and Prefabs Library
Go to modify-> load objects-> then go to the folder you have downloaded->open the folder and pick the building you want.
If you want to change single object you have to ungroup the building you got. (Group->ungroup)