1. First clean the green walnuts.

2. Then put the green walnuts into the pot and soak them for thirty minutes.

3. Then turn on the heat and cook for thirty minutes until the soup changes color.

4. Then use a brush to evenly apply the cooked soup to the hair.

5. Put on a shower cap and let it sit for an hour.

6. Then wash your hair with clean water so that your hair is dyed black.