You cannot copy files or folders to a CDROM---you have to use some kind of "burning" SW (e.g k3b)
You don't say what the problem is with k3b, but there might be an issue with permissions. To test this, you can run it as root. In a terminal, enter "su" to become root, and then "k3b". Or, on something like Ubuntu, just one step: "sudo k3b".
Tell us more about your system--what distro, etc.