How do you burn a CD on itunes with an external CD drive?

1. Put everything you want in a playlist (File> New Playlist),
2. Connect your external drive and insert a blank CD (make sure that it says CD-R on the front)
3. Go to File > Burn Playlist to Disc
4. Give your CD a title and choose a speed (best if it is set to 'Maximum possible')

Hope this helps!