I'm going to assume that you're modelling with gmax and have compiled the mdl file.

Basically, you have to copy the aircraft.cfg, *.air and other files/folders from an existing airplane (hopefully one similar to what you're modelling) and start tweaking from there.

Required reading now:

aircraft container SDK
aircraft creation SDK...

panel creation - once you want to modify the aliased panel, but for your first compilations, just alias to an existing airplane's panel.