If you have quite a lot of old Audio CD collections and wanted to listen those songs in mobile, iPod or iPad. Then you need a tool to rip the audio files from CD to mp3. There are quite a lot of free tools available.
Do you know that the same thing can be achieved using windows? Yes, Windows Media Player that comes with windows operating system can very much rip your Audio CD songs to mp3.
I stumbled upon this post/guide on how to convert to mp3 from Audio CD. Hope it helps