I am running windows 7.....
and FSX,  Idownloaded and unzipped a few add ons, but cannot find the FSX file, and dont know how to edit it, the instructions on the site work for XP, not windows 7, any help will be greatly appreciated.

If you install that way, you may have problems if the add-on has additional sound, effects and gauge folders.

To install:

Unzip the download to either the desktop or a "down-load" folder.

Open the estracted folder, locate and read the "Read Me" file.  Most of the time the "Read Me" will be located in the extracted folder.  Usually, the read-me will contain installation instructions.

All you have to do is follow the instructions in the read me, but the standard is copy/paste the aircraft's folder into the "Airplanes" or whichever folder it would belong in (rotocraft, boats....).  If the addon also has a separate sound, gauge or effects folder, open them, and copy paste their contents to the appropriate FSX folder (effects sometimes also contain .bmp files, which need to be installed in the effects/texture/ folder).

As to the location of FSX, itself, In Win7, it's default location is "C:/Program Files (x86)/Microsoft Games...." but many suggest installing any of the flight sims in their own directory on the "C" drive, and some even suggest on a separate drive.  Mine is installed at C/FSX.  The main advantage is not having to jump through any security hoops when editing the aircraft.cfg file for add-on textures or other .cfg edits, and supposedly, it saves on disk access time.