Adding Aircraft: Which Folder to Use for FSX?

Hey every one! I am knew to this site, but not to Flight Sim. My question is how do I add addon aircraft. Do I just drag>drop the files into the Flight Sim prgram files folder? IIRC in fs 2004, there was a file "Aircraft" I would put the file in that folder. Anyway, some help would be awesome, thanks!

Follow this.

https://flyawaysimulation.com/knowledge/page/34/installing-addon-flight-simulator-downloads/