Transfer songs from iPod to library that have not been purchased through iTunes?

I have a playlist on my iPod that eventually I need to get onto a CD. To do that, apparently I have to have all the songs in an iTunes library. However, not all my songs have been purchased through iTunes, so I don't know how to transfer all my music from my iPod, into my iTunes library, so that it will be on my computer so I can burn the playlist onto the CD. It has to go from ipod to itunes library to computer to CD. Bleh. Since I have downloaded a good chunk of my music from other sites and my cousin has also put music from unknown websites on my iPod, I have no idea what to do now. The compute won't let my drag the songs to the desktop or folders or anywhere. HELP!! ): (My computer is a macbook pro from like 2010, idk what model.)