To get started with React.js, you'll need to have Node.js and npm (Node Package Manager) installed on your system. Here are the steps to install React.js:

1. Install Node.js and npm :

   - Go to the official Node.js website: [https://nodejs.org/](https://nodejs.org/).
   - Download the installer for your operating system (Windows, macOS, or Linux) and run it.
   - Follow the installation instructions provided by the installer.

   Once Node.js and npm are installed, you can verify their installation by opening a command prompt or terminal window and running the following commands:

   node -v
   npm -v
   

   This will display the installed versions of Node.js and npm. if not display mean some issue to install in your system

2. Create a New React App:

   React provides a tool called `create-react-app` that sets up a new React project with a default configuration. To create a new React app, open your terminal or command prompt for the perticular folder and run the following command:

   npx create-react-app project-name

  This will create a new directory called `my-react-app` with a basic React application structure.

3. Navigate to the New Project:

   Use the following command to navigate into the newly created project directory:

   cd project-name
  

4. Start the Development Server:

   Once inside the project directory, you can start the development server using the following command:

    npm start
 

   This will start the development server and open your default web browser with the React application running. As you make changes to your code, the app will automatically reload.

That's it!