yes, you have to mount it first. mounting means to attach a filesystem from a removeable disk or so to the filesystem tree of your root partition. the system needs to know three things in order to mount something succesfully:
1. what kind of filesystem do you intend to mount?
2. where is that filesystem located?
3. where to attach the foreign filesystem/file tree to your native one?
thus the mount command needs three arguments. the syntax is like this: mount -t TYPE FROM WHERE. the WHERE is usually the /mnt directory. modern distros though have a /media directory where they mount stuff. it doesn't really matter. pick one. but beware once you mounted something in a directory the former content of it is not accesible as long as the cd/dvd is mounted. follow these steps ('#' is the root prompt and '$' the user prompt):
1. insert cd/dvd
2. make sure you know which device your cd/dvd is (usually /dev/hdc or /dev/hdd)
3. pick a mount directory (here: /mnt)
# mount -t iso9660 /dev/hdc /mnt
the option -t specifies the filesystem type. for cd/dvd this is iso9660. /dev/hdc is the your cd/dvd device...
5. now the content of your cd/dvd is displayed in /mnt (or whereever you mounted it). do for example:
NOTE: you can't simply hit the open button on your cd/dvd drive to remove the cd/dvd. you must unmount the cd/dvd first. to unmount a filesystem your linux needs to know only one thing. WHERE the file tree is. so it's sufficient to do:
note that the command is NOT unmount BUT umount. now you should be able to remove the cd/dvd
EDIT: i wasn't faster! damn