Everything in linux is a file. There are no drive letters like in windows. To use a cd you have to mount it to a directory first. To do this you need to know which ide channel the cd drive is on and whether it's master or slave. Ide channel one master is called hda. Ide channel one slave is called hdb etc etc. If hda is split into multiple partitions than they would be labeled hda1 hda2 hda3 etc. So anyways, to mount a cd that was master on the second ide channel, you would first need to create a directory to mount it to. The normal spot for this is /mnt/cdrom.
Here are the commands you'd use
su (this command allows you to change to the root user)
mkdir /mnt/cdrom
mount -t iso9660 /dev/hdc /mnt/cdrom (this command mounts the cdrom drive, with type iso9660 filesystem, into folder /mnt/cdrom)
cd /mnt/cdrom
ls (list files)