First list down the CD/DVD devices connected to your machine and find the device name. Some of the tools that comes handy in an Ubuntu machine are ‘wodim’, ‘genisoimage’

Wodim stands for Write Data to Optical Disk Media. If you don’t have the software installed in your Ubuntu release do an apt-get

$ apt-get install wodim

To know more about wodim and its parameter definition try man on wodim

To list the CD/DVD devices on the machine, issue

$ wodim –devices

wodim: Overview of accessible drives (2 found) :
————————————————————————-
0 dev=’/dev/scd0′ rwrw– : ‘HL-DT-ST’ ‘CD-RW GCE-8481B’
1 dev=’/dev/scd1′ rwrw– : ‘HL-DT-ST’ ‘DVD-ROM GDR8161B’

Our read-write CD device is in /dev/scd0. So our command for burning the .iso image

$ wodim dev=/dev/scd0 driveropts=burnfree -v -data ubuntu8desktop.iso

To burn audio files

$ wodim dev=/dev/scd0 driveropts=burnfree -v -audio one.wav two.wav three.wav

Further read
i) ubuntu guide http://ubuntuguide.org/wiki/Ubuntu:Feisty/CDDVDBurning

ii) ubuntu site https://help.ubuntu.com/community/CdDvd/Burning