api files?

I've been sent a lot of api files - Red 'plug-in' things but with no instructions how I use them for the sceneries I'd like to use them in.....can someone help me out with how I use them?
Flight Simulator and other chat
https://forums.simviation.com/phpBB3/
https://forums.simviation.com/phpBB3/viewtopic.php?f=16&t=38778
You want to go to this link- http://www.fsdeveloper.com/forum/downlo ... &sort=date
...and get 2 programs.
ModelConverterX and Library Creator XML 2.0 (on page 2).
MCX will import those APIs and convert them to .mdl files.
Library Creator XML 2.0 will compile those models into object libraries that you can use with programs like EZ-Scenery to place the objects.
While your there register for the forum and thank Arno Gerretsen for creating these gems and giving them to us for free!
cheers,
Joe