Ok I can't figure this damn skill out at all. Where do you get the magic essence. How the hell do you do this skill?! All the others seemed easy to me but this one has me pissed off.
Syntax has it about right. When you get the tradeskill you also recieve a disenchant spell. You cast this spell on magical items and recieve magical essences. The more powerful/higher level the item, the higher number/higher quality of the essences.
You then use these essences to enchant new items. Tada.
The thing that is confusing about disenchant is that, unlike all other tradeskill-related abilities, this one is a SPELL. Click your spell tab rather than abilities to find it.