So I've inherited the My Book World Edition from someone

But let me be clear, it’s just the enclosure, which I am assured works perfectly well. The problem I’m having, it finding the software for the pre-installed drive to install on a replacement drive so I can use it. Where can I get this? And how should I partition, what file system should be used for those partitions? Is there someone who can/will help me with this?

Don’t know if that is possible, but you provably need to use a hard drive that is the same model of the old one.