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.
Jaef -- 60 Hunter -- Crushridge
Shiesty -- 60 Warrior -- Crushridge