I don't know if I am doing this correctly but I've been putting them in the Tray Folder; however they aren't showing up (or at least I can't find them in the game/my library). Can someone point me to a step-by-step guide where to install them and where to find them? I am about to check on youtube for a video on it. Thanks in advance for any help. I appreciate it a great deal.

So I found a video on Youtube and I've done it right. I found one of the houses in my library.

Installing Blueprint Files