you have a couple options.
first you have to be wearing them
you can either:
1. click the magic wand on the right of the text box, then double click the one you want
or
2. say the "magic word" you see when you single click each magic pin in the magic wand button.
As far as I know, the magic words are as follows:
Invisibility: Spooky!
Buried in treasure: BlingBling!
Pirate Costume: YohoYoho!
Teleportation: Jump!
Dancing Inferno: Inferno!
Fireworks: Rocket!
Cursed Storm: BoomCrash!
Each must be typed with caps where I indicated and with the ! at the end.

You can only use the magic if you already have the pin.
Good luck!