How can I get my iTunes Genius to recognize all of the songs in my library?

So I recently got like 65 GBs of music that i transfered from my friends’ iPods to my HP laptop. (Which if you didn’t know you could do, it’s pretty bitchin’.) But none of that music is recognized by the Genius in iTunes, because when I try it gives me a message that the music I’m trying to make a Genius playlist fo,r was not imported using iTunes, and that I should try impoting the song again using iTunes, which I took as, “buy the song using iTunes.” Is there anyway to get the Genius to recognize the 65 GBs worth of music so that I can create genius playlists for all of my library?