It will differ slightly because people have zipped up the files differently. Check the readme that is included with each file.

[b]Usually[\b] you will just unzip the downloaded file into your aircraft directory and that is all that is required. Some will not unzip into it's own directory. If that is the case, make a new directory named for the aircraft, and move the files into it.

Each aircraft must be in it's own directory, I believe the directory is the name displayed for the model in the sim.
Sometimes there is a *.wav file that will have to be moved to the AFP(D) sounds directory.
For deluxe the older models made for AFP will not have an image of the plane, or a comment file. You will have to make them yourself. They are named !QUOT!preview-{name of model}!QUOT! 1 text file, and 1 preview image.
A few models use channels for dropping bombs, folding wings, moving canopy. You will have to assign something to control that channel if you don't already have it.

Attempt at a sample of the directory structure:

AFP(D)
|
+aircraft
| |
| +OMPBipe
| |
| +Corsair
|
+sounds

The OMPBipe is a good example since it is one I know is packaged right and includes the new files used by deluxe. Unzip the file in your aircraft directory and make sure it created a directory called OMPBipe and your done. Use that one as a reference for what files should be where.

Hope this helps.
If I made a mistake, sorry I'm not at home atm to verify the directory names.
Dale