In Linux any hard disks, USB devices and optical devices has to be mounted before you can access their contents. For this reason it's handy to know how to mount from the terminal. So, open a terminal and type:
mount -t iso9660 /dev/sr0 /mnt/sr0
to mount an optical device. The instruction is simple. It tells that you must mount with the specified coding what and where.
To unmount the mounted optical device type in the terminal: