Ok so first go to the stylists arena. I'm not sure if you've unlocked it though. If you have it then go there and tap exchange near one of the corners or edges of the screen. Then you will see the starlight shop and your starlight coins. Each recipe costs certain amounts of starlight coins. Hopefully you can buy yours!
Comment found on Love Nikki-Dress UP Queen: I ' m on level...
For the stylists arena, stuff doesn't need to look good (coats can be too small for the dress or gloves cover your bracelet etc.) It's judged on a technical level by robots! Just put on a lot of stuff that matches the theme! Worse scenario is you fail. You still get star coins and you don't get demoted out of your rank so no biggie ;)
Comment found on Love Nikki-Dress UP Queen: Does anybody have any tips...