Importing Music

I am incredibly frustrated trying to add the music that I want to my movie.  When I select "import audio or music" I select my iTunes tab, and it only gives me about 5 songs I can use.  It also doesn't even come close to listing my entire iTunes library.  I have even tried to change the format of the songs I want to MP3's but that isn't working either.  How do I get the music that I want?!