How to write a novel about Lin Yun Er's Mermaid Princess?

The story of Lin Yun 'er's Mermaid Princess can be referred to as follows: The protagonist of the story was Lin Yun `er, a young and beautiful girl with the identity and legend of the Mermaid Princess. On a mysterious island, Lin Yun `er's parents died in an accident and she was forced to leave her hometown to inherit her family's mission and become the Mermaid Princess. Lin Yun `er had a difficult childhood on the island, but she was not a lonely person. She had a loyal jellyfish friend, a beautiful mermaid sister, and various other sea creatures. She learned how to get along with sea creatures and gradually grew into a brave and caring mermaid princess. During one of her expeditions, Lin Yun `er discovered a mysterious crystal that had magical powers. Lin Yun `er decided to use the crystal to help the humans solve some problems. However, the power of the crystal also brought some danger. During her adventures, she met some kind humans who helped her control the power of the crystal and protect her from evil forces. At the climax of the story, Lin Yun `er had to use the power of the crystal to save the entire island. In the process, she encountered some difficulties and challenges, but her courage and wisdom made her successfully complete the task. In the end, Lin Yun `er became a hero, and people paid their respects to her, making her a legend on the entire island. At the end of the story, Lin Yun `er returned to her hometown to start a new life. She learned how to balance her identity and mission to become a true hero.