Okay, so I know where to put .sav files, I just do not know how to use them in-game. Any suggestions???
Um. What do you mean by “use them in game”?
Same as the way you spawn a downloaded entity or npc.
A .sav file is created when you click “save game” in a singleplayer session; The information telling about the location and orientation of whatever is spawned at that moment in that map will be in the .sav file.
Put simply, load the .sav file in the “Load Game” menu, and whatever the creator created will appear just as he left it when he saved.