Creating a custom plugin

[Adnerw]

Hi
I am new and i am trying to learn Superset.
I would like to create a new plugin.
I did yarn install && yarn build and after running yarn storybook but when I open the localhost:9001 in the preview appears this:

ERROR chartType="my-chart" —Error: Item with key "my-chart" is not registered.

This is a file Stories.tsx

import React from 'react'
import { SuperChart } from '@superset-ui/chart'

export default [
  {
    renderStory: () => (
      <SuperChart
        chartType="my-chart"
        width={800}
        height={500} 
		  />
    ),
    storyName: 'Basic',
    storyPath: 'plugin-my-Chart|myChartPlugin',
  },
];

and this is a my index.js

import ChartMyPlugin from '../../../../superset-ui-plugin-chart-my/src';
import Stories from './Stories';

new ChartMyPlugin().configure({ key: 'my-chart' }).register();

export default {
  examples: [...Stories],
};

what should I do?
Thanks in advance

Andrea