No music visible In library

I have just bought a MacBook air and am trying to copy the music files from my old windows pc onto the new pc. I have used drag+drop and by using the add to library instruction from the file drop down. I can see the folders and files in finder but they do not appear in inlayer under the music folder. This folder is empty but I have transferred purchased music from an ipod which is visible and playable. To confuse things further, all my applications have been moved over? Can you please help