Itunes problem

I have my itunes folder set to my music folder, so when I drag new stuff into the music folder, it should automatically show up in my itunes library. Instead, when I move files into my music folder, it does not show up, so I drag it into the itunes library. Later on, I will have a lot of doubles in my library. What is this?

Don't think Windows think Mac.
Don't create any music folders.
Just add music into iTunes and allow iTunes to manage your library