In Linux, you have to mount a CDROM.
If you are using KDE or gnome, you can do this by right clicking on the desktop and then follow your nose (ie DISK and then choose CDROM or mount CDROM etc)
If you want to do it manually, you need to be root. Do this by logging in as root or in a terminal type in su (which means superuser mode) You will then need root password.
get to the folder mnt (type cd /mnt)
See what's there (type ls) and look for something like CD or CDROM
If there isn't anything like that, type mkdir cdrom
mount /dev/cdrom /mnt/cdrom
You can now read your cdrom in that folder so just cd cdrom to get there.
Alternatively use your file manager (nautilus, konqueror etc)
If you need to remove the cd, you need to unmount it. Make sure you are not in the folder /mnt/cdrom and that nothing is using that folder and then type
Notice the spelling is umount not unmount.