there are several terms that go with partitioning
primary partition >>>> extended partitions >>> logical drives
a logical drive is different from a physical drive / a physical drive (like an 80 gig maxtor) you can actually hold in your hand >>>> a logical drive is a drive partition like D,e,f, g, h, I etc they are drives as far as logic goes >>> but a logical drive can no tbe held in your hand; so to speak that should help to understand the diference.
there are primary partitions and extended partitions / extended partitions are the ones that can be configured into more drive letters
maybe this will explain better >>>>http://www.bleepingcomputer.com/tutorials/understanding-hard-disk-partitions/
if you can use them >>> you did fine !!!