The powder you buy, and bring to an appropriate body mod artist (or DIY if you’re into that). Its a dermal incision in the pattern you choose, then packed with the glow powder and kept moist (but not wet) during healing. The healing phase is arguably the most important for good results. There’s a good write up on how to here.
You can buy glow powder from either Abyss Walker or Dangerous Things.
Hope that helps, feel free to ask more questions to myself or others if you have them.