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/>

1     1. install react-bootstrap
2
3                npm install react-bootstrap bootstrap
4
5
6     2. import css file in your index.js or app.js
7
8                import 'bootstrap/dist/css/bootstrap.min.css';
9
10             <link
11              rel="stylesheet"
12              href="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css"
13              integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T"
14              crossorigin="anonymous"
15             />
16
17      3. import components like
18
19                import { Button } from 'react-bootstrap';
20

1	npm install bootstrap
2

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