OK. Flat area first. Select New Misc Object/Flat Area from the Right-click options. The Area16N (BGL) type should be selected by default. The Altitude should be the same as your airfield. Drag the points of the Flat Area to surround your airfield. You can add points as you wish. 4 will do to start with. It can tidied up later. The A16N Flat Area can be almost any shape with up to around 50 points. Use the Export Scenery Wizard to export the finished airfield, making sure the _A16N.bgl option is checked.
For the static aircraft try M98toBGL posted here.
http://www.simviation.com/fsdesign_scenery5.htmUse it to create API macros from existing 3rd party aircraft. Import the API macros into FSSC. Simple FS98/CFS1 designs work best as static scenery objects.
My tute shows the basics for adding new airports to the MB database.
http://www.simviation.com/lair/Scene2MbDb.htmlPS. Once you have created your airfield it can be moved to another location by changing the Airport entries & co-ords in FSSC Scenery Properties. Remember to save the new field under a new name.