Also: React Router Anatomy of a react component:

import React from 'react';
// Alternative:
// import React, { Component } from 'react';
// class FirstComponent extends Component {

class FirstComponent extends React.Component {
  render() {
    return (
      <p>Hello</p>
    )
  }
}
// 'return' can only return one element! If you need more than one, wrap the elements in a div
export default FirstComponent;

Comment in jsx: { /* This comment */ }

To be able to reference this in a component, on form submission, you can do so in an onSubmit function: onSubmit={(e) => { this.submit(e) }}

Alternatively, you can use a "constructor" before the component is instantiated:

class FirstCompnent extends React.Component {
  constructor() {
    super();
    this.submit = this.submit.bind(this);