That needs some clarification.
1. What Itunes music?
2. What kind of CD?

For CD's, there's the audio CD (up to 70 minutes of music, can be played in any CD-player) and the data-CD (can contain much more types of file, can't be played on a standard CD-player).

And Itunes doesn't really contain the music. It's just a player that knows where the music files are located on your hard disk.
But, indeed, it has the option to burn selected music from its library to an audio-CD. Here's a link about it:
http://support.apple.com/kb/TA38263 For not-DRM-protected mp3's (mp3's you didn't buy in the iTunes shop), however, you can also use other programs than iTunes to convert them to cd-audio format and burn to CD.

Kees