somehow lost my whole library of downloaded planes

I added steam fsx to my computer, and download plenty of files with new planes, some of them unzipped correctly into the airplanes folder and some didn't, some without panels, some no sound, blah blah. i would move those files from the airplanes for to the texture, or sounds, or effects file as directed and nothing would change?So im not good at this basic stuff at all clearly but understand how it should wrk it just never does 100% of the time. Ok, so i tried deleting the files off my laptop since there obviously lost in another file somewhere the fsx isn't seeing them so they don't show up in FSx to use? I saved all the extra stuff, basically a backup to an external drive and redownloaded FSX from steam, and now steam isn't using the normal / programfiles86x/FSX whatever to store the data the second time around? So i no matter what i do to try and download and add planes, missions, files or anything im just stuck with the plain ass basic game with default planes only?> how can i find and redirect the newest FSX im using to look elsewhere to find my aircrafts/ rotorcrafts/ missions data? or even be able to download new stuff even? Im literally stuck, and a newb clearly when it comes to this!!! Please help.....

-Joey