If anybody would like to correct me, please do, I'm not 100% sure I've gotten everything right
You seem to doing fine so far.

Ok I downloaded Fssc. will this work with FS9? I know that FS9 is alittle diffrent than FS200 and FS2002 ?
Hi Batman. Yes it will work fine apart from a few features. For example: the AFD BGL is not recognised in FS9. This lists new airports on the FS9 Airport menu. You can use the FSSC Menu Object instead.*
I suggest you familiarise yourself with FSSC (or Airport for Windows) before creating your own scenery objects. There are plenty of 3rd party API macros of all descriptions posted here & on other sites. Not sure about Airport but a selection of macros comes bundled with FSSC. These can be imported into either program. To start with, try placing a few of these macros on an existing airport. Taking things in easy stages is less confusing & generally works out quicker in the end.
Good luck.

*PS. Once it's complete you can use AFCAD to add the FS9 menu entries to your project. Let's do one thing at a time.