CDR won’t let me add files (read-only?)

I copied a few files off of floppy disks and saved them to my Windows ME. When I put a disk in D: drive and try to copy or save my files to that disk, it says access denied, folder is marked as read only. I know there is no files on the disk and I’ve tried at least six or seven disks and all say the same thing. I odn’t understand. What can I do to fix this?