added Routes with route to react start and tornado backend api to App.js

import logo from './logo.svg';

import './App.css';

import React from "react";

import { BrowserRouter as Router, Routes, Route, Link } from "react-router-dom";

import HomeComponent from "./components/HomeComponent"; 

import MessageComponent from "./components/MessageComponent";

// import logo from './logo.svg';

// import './App.css';

function App() {

  return (

    <div className="App">

      <header className="App-header">

        <img src={logo} className="App-logo" alt="logo" />

        <p>

          Edit <code>src/App.js</code> and save to reload.

        </p>

        <a

          className="App-link"

          href="https://reactjs.org"

          target="_blank"

          rel="noopener noreferrer"

        >

          Learn React

        </a>

      </header>

    </div>

    // <div className="App">

    //   <header className="App-header">

    //     <img src={logo} className="App-logo" alt="logo" />

    //     <p>

    //       Edit <code>src/App.js</code> and save to reload.

    //     </p>

    //     <a

    //       className="App-link"

    //       href="https://reactjs.org"

    //       target="_blank"

    //       rel="noopener noreferrer"

    //     >

    //       Learn React

    //     </a>

    //   </header>

    // </div>

    <Router>

      <Routes>

        {/* Home route */}

        <Route path="/" element={<HomeComponent />} />

        {/* Message route */}

        <Route path="/message" element={<MessageComponent />} />

      </Routes>

    </Router>    

  );

}