The /media directory implies that udev and hal may be used to automount CDs and DVDs. Insert a formatted CD or DVD. Do you see a popup?
Does Mephis use KDE or Gnome or a different environment. If it is KDE, enter "sysinfo:/" in the konqueror browser. Does the disk show up there.
If you have the "halmount" program try using it. You can use either the device, label or mountpoint to mount a disc. How things should work is that the Label is used to create a new mount point for the disc. So inserting a disk with the label "MyVids" should create a mount point /media/MyVids after you respond to mount the device.
If you don't have hal and udev, then you could try manually mounting the disc.
An entry in /etc/fstab like:
/dev/hdc /media/cdrom iso9660 ro,user,noauto,unhide 0 0
may help you mount the device manually. The "noauto" option will prevent the system from trying to mount the device when you boot. The "user" option will allow you to mount it with the command: "mount /media/cdrom" without having to use su or sudo to do it as root. (The "/bin/mount" command is suid, and checks for the "user" entry in /etc/fstab to determine whether you can mount it.) I used /dev/hdc for this example. Use the device name for your CD/DVD device.