First you need to install the nodejs from nodejs.org website.
There are many nodejs versions and you can download as you need.
Then install it.
You need to test npm package installed or not in your computer.
Press Window+R then type cmd and press enter
In your terminal or cmd, type npm –v like this
Then let’s create reactjs hello world example
In your terminal, type npx create-react-app helloworld
A few minutes long in this process.
If finsh type go your path => cd helloworld =>npm start
You will get this result in browser localhost:3000
In your src/App.js
type <h1>Hello world</h1>
you will get like this