1//1.run following commnad in cmd:
2npm install bootstrap --save
3//you can now use bootstrap component. example:
4import { Button } from 'react-bootstrap';
5
6//2.or  add this to index.js:
7<link
8  rel="stylesheet"
9  href="https://cdn.jsdelivr.net/npm/bootstrap@4.6.0/dist/css/bootstrap.min.css"
10  integrity="sha384-B0vP5xmATw1+K9KRQjQERJvTumQW0nPEzvF6L/Z6nronJ3oUOFUFpCjEUQouq2+l"
11  crossorigin="anonymous"
12/>

11.run command in cmd
2npm install react-bootstrap bootstrap
3
42.after install add this to index.js
5import 'bootstrap/dist/css/bootstrap.min.css';
6
7//You may want to add individual components like 'Navbar',
8 // or 'Button' rather than the entire library.
93. add this, or similar to the js files that would be using the individual components
10import {Navbar, Nav, Button} from 'react-bootstrap';

1	import $ from 'jquery';
2	import Popper from 'popper.js';
3	import 'bootstrap/dist/js/bootstrap.bundle.min';
4