make a playlist in itues that does not exceed 680mb. when full (or you have all you want), it should have about 800 ish songs in it. maybe over 1000. put a cd-r in your mac and either
a) select all the songs and drag them onto the icon on the desktop of the cd, and press burn, or
b) in itunes preferences, set burning to MP3 cd, instead of Audio CD. then hit burn on the playlist.