Spells are learned and collected in the Wizard's Companion. They are segregated into Everyday Spells (normally cast out of battle) and Battle Spells cast during battle (or moments of conflict) to attack the target.
Occasionally, a battle spell will be used in a non-combative manner, as in Ding Dong Well or Glittering Grotto, but such instances are more exceptions than a rule.
The spells that you get from The Fairy Godmother are spells that can only be used by fairies. You can not use these, because they can not be used by humans, only by fairies. The only exception is the Poison Apple spell.