Classic British Flight Sim

OK i need some help please....I have numerous programs to add files to the default and modded airports..but and a big but...I can add API scenery no problems in SceneGenX no probs but i cannot seem to add any other sort of file (.bgl) so that they show in game? I have read the ruddy manuals baclwards and still don't know where i am going wrong ?

Anyone with experience of scenery prograns could you lend a hand?

Tony