Importing Prefabs

[Supertint]

Sorry if this is a rehash, I did look for info/video but could not find the answer.   How to import a prefab that you downloaded from the net.   So I found a prefab I want to put into an existing game...  Where do I put that file(s)?  It comes zipped...  unzip to where?    I managed to the C:\7D2D\alpha19\war3zuk\War3zuk_Alpha_19_AIO_OverHaul\Data\Prefabs .   There were four or five files...  went to edit the prefab, found it, tried to place it in the world and it wiped the map...  Game gone...  no worries there, I just want a video or step by step as to the way to import a prefab into an existing map.   I did find a video that kinda shows this, but using prefabs that are already part of the game...  How to add one new from the net, like lazmans church?  

 

Thank you!!!  

 

Again, please accept apologies if this has been covered, please, if you have a link splaining this, post it for me