Hi Paolo,
I suggest you forget how to do things without tools at first. There are enough of them available from this site.
You could do it in several ways.
If you want to have a seperate folder with library objects for a particular airport, you make a library with LibraryCreatorXML give it the name you want and add the mdl('s) to it. If you want to have effects in the mdl's, then attach the effect(s) to the mdl with ModelconverterX.
Now, as for your airport, make that with ADE, import the newly made library objects bgl to the Library Object Manager (LOM) that is built in in ADE, move your mouse to the spot where you want your object, right click and add your Library Object. Your object will be in the ADE workfolder.
Or, when you do not want to make it a library object, you can add the model to ADE (list>models>add>save>close>right click with mouse on spot where you want the model, > add model>select the model). That way the model will be directly inside the ADE airport.bgl.
You can also do a "split compile" with ADE, in which case all the airport parts go to the ADE_xxx_xxx.bgl and the objects go to the ADE_xxx_xxx_OBJ.bgl.
This is just one way of doing things, of course, (the way I am familiar with) but there are more programs that you can use.
As for the effect on your power plant, I have not the faintest why it does not show with you and George, but have you already tried to change the name of the effect, delete the stoptemp entry, and set the lifetime of the emitter to 0 ?
PS Do NOT change anything in the scenery/world/scenery but, for instance, in the settings/scenery library list once you have started FSX.