How to create an initial value in Lexical rich text, then edit it?

I use the Lexical library from Facebook as a WYSIWYG component but I don’t know how to create the initial value?
After searching for a long time, I took the initiative to throw it on this forum, hopefully someone can help.

this my code:

import ExampleTheme from "./themes/ExampleTheme";
import { LexicalComposer } from "@lexical/react/LexicalComposer";
import { RichTextPlugin } from "@lexical/react/LexicalRichTextPlugin";
import { ContentEditable } from "@lexical/react/LexicalContentEditable";
import { HistoryPlugin } from "@lexical/react/LexicalHistoryPlugin";
import { AutoFocusPlugin } from "@lexical/react/LexicalAutoFocusPlugin";
import LexicalErrorBoundary from "@lexical/react/LexicalErrorBoundary";
import TreeViewPlugin from "./plugins/TreeViewPlugin";
import ToolbarPlugin from "./plugins/ToolbarPlugin";
import { HeadingNode, QuoteNode } from "@lexical/rich-text";
import { TableCellNode, TableNode, TableRowNode } from "@lexical/table";
import { ListItemNode, ListNode } from "@lexical/list";
import { CodeHighlightNode, CodeNode } from "@lexical/code";
import { AutoLinkNode, LinkNode } from "@lexical/link";
import { LinkPlugin } from "@lexical/react/LexicalLinkPlugin";
import { ListPlugin } from "@lexical/react/LexicalListPlugin";
import { MarkdownShortcutPlugin } from "@lexical/react/LexicalMarkdownShortcutPlugin";
import { TRANSFORMERS } from "@lexical/markdown";
import ImagesPlugin from "./plugins/ImagesPlugin";

import ListMaxIndentLevelPlugin from "./plugins/ListMaxIndentLevelPlugin";
import CodeHighlightPlugin from "./plugins/CodeHighlightPlugin";
import AutoLinkPlugin from "./plugins/AutoLinkPlugin";
import React, { useEffect, useState, useRef } from "react";
import { useLexicalComposerContext } from "@lexical/react/LexicalComposerContext";
import { ImageNode } from "./nodes/ImageNode";

function Placeholder() {
  return <div className="editor-placeholder">Enter some rich text...</div>;
}

const loadContent = async () => {
  // read from database, local storage, etc.
  const value =
    '{"root":{"children":[{"children":[],"direction":null,"format":"","indent":0,"type":"paragraph","version":1}],"direction":null,"format":"","indent":0,"type":"root","version":1}}';
  return value;
};

const editorConfig = {
  // The editor theme
  theme: ExampleTheme,
  // Handling of errors during update
  onError(error) {
    throw error;
  },
  // Any custom nodes go here
  nodes: [
    HeadingNode,
    ListNode,
    ListItemNode,
    QuoteNode,
    CodeNode,
    CodeHighlightNode,
    TableNode,
    TableCellNode,
    TableRowNode,
    AutoLinkNode,
    LinkNode,
    ImageNode,
  ],
};

export default function Editor() {
  const initial = {
    root: {
      children: [
        {
          children: [
            {
              detail: 0,
              format: 0,
              mode: "normal",
              style: "color: #f5a623;",
              text: "Hello World!",
              type: "text",
              version: 1,
            },
          ],
          direction: "ltr",
          format: "",
          indent: 0,
          type: "paragraph",
          version: 1,
        },
      ],
      direction: "ltr",
      format: "",
      indent: 0,
      type: "root",
      version: 1,
    },
  };

  const [editorState, setEditorState] = useState(JSON.stringify(initial));
  const [value, setValue] = useState(null);

  const OnChangePlugin = ({ onChange }) => {
    const [editor] = useLexicalComposerContext();
    useEffect(() => {
      return editor.registerUpdateListener(({ editorState }) => {
        onChange(editorState);
      });
    }, [editor, onChange]);
  };

  const onChange = (state) => {
    // Call toJSON on the EditorState object, which produces a serialization safe string
    const editorStateJSON = state.toJSON();

    setEditorState(JSON.stringify(editorStateJSON));
  };

  console.log(editorState); // show value before parse to html

  return (
    <>
      <LexicalComposer initialConfig={editorConfig}>
        <div className="editor-container">
          <ToolbarPlugin />
          <div className="editor-inner">
            <RichTextPlugin
              contentEditable={<ContentEditable className="editor-input" />}
              placeholder={<Placeholder />}
              ErrorBoundary={LexicalErrorBoundary}
            />
            <HistoryPlugin />
            <TreeViewPlugin setValue={(val) => setValue(val)} />
            <AutoFocusPlugin />
            <CodeHighlightPlugin />
            <ListPlugin />
            <LinkPlugin />
            <AutoLinkPlugin />
            <ImagesPlugin />
            <OnChangePlugin onChange={onChange} />
            <ListMaxIndentLevelPlugin maxDepth={7} />
            <MarkdownShortcutPlugin transformers={TRANSFORMERS} />
          </div>
        </div>
      </LexicalComposer>

      <div dangerouslySetInnerHTML={{ __html: value }} />
    </>
  )
}

the documentation is very minimal and I don’t understand it, what should be done to modify it? and is there a tutorial or answer regarding this?