How do you make an iso?

how do you make an iso?..also what does it mean to ghost something?

Most CD/DVD burning packages like Nero or DiscJuggler, as well as DVD video programs like DVD Decrypter or DVD Shrink support ISO image creation. There are also shareware programs like MagicISO written for this purpose. In Linux [and Windows XP running Cygwin], mkisofs is a good way to create ISO images using a command line.

Ghost is a backup/cloning/mirroring software: http://www.answers.com/topic/ghost-software, so I suppose ‘to ghost’ something is to backup/clone/mirror it.