i am guessing you will use the dream catcher for its intended purpose. its a charm, making it is the spell. the bead in the middle is bate to catch bad dreams, they get tangled in the web like shape, and [hung by a window] the morning light destroys the bad dreams. look into its meaning, and how to make one, store bought dream-catchers are for profit, no energy goes into making them. plus the materials are fake and/or cheap, using real bird feathers for instance can grant it more energy.
if you do purchase one, or wish to enchant one further, you can cleanse it with say, then say a chant, and charge it with energy. it really isn't necessary though if you made it.