Here are the steps to use Flexi Rods for super-defined curls:

1. Start with freshly washed hair. You want to make sure your hair is fresh, clean, and good to go before you start.
2. Detangle your hair.
3. Apply foaming mousse.
4. Wrap your hair around the flexi rods.
5. Sit under a hooded dryer or air-dry.
6. Remove the rods.

Here's a video tutorial by The Vintage Hipster that can guide you through the process: