Be more specific, what are you trying to do? I suppose you want to access your CD-ROM and floppy and you are trying to use DOS commands - guess what, linux ain't DOS, for linux to see the contents of your CD-ROM you must mount CD-ROM first. Issue as root in Xterm or Konsole or whatever terminal emulation you are using:
mount -tiso9660 /dev/cdrom /mnt/cdrom
for this to work you must make certain that /mnt/cdrom exists on your system and /dev/cdrom is pointing to the actual CD-ROM drive, if you are new to linux I suggest getting a linux book that covers using linux, or search the net for linux to see what it can offer.