>>"When I do ls in /mnt/ it appears cdrom/ floppy/ hd/. Is that right?"
That's fine. Those are the default three folders, where CD-ROMs and floppies are mounted respectively. It's safe to use hd/ to mount disk partitions, since I've never really seen that folder used elsewhere.
Of course, if you so desire, nothing stops you from creating your own folder. It's not required, but it makes finding things a bit easier. For instance, I mount my NTFS partition to a folder I made called /mnt/ntfs.