To install React and create your first app, you can follow these steps:

1 Install Node.js and npm (Node Package Manager) on your computer. You can download and install the latest version of Node.js from the official website: https://nodejs.org/en/download/.

2 Once you have installed Node.js, open your terminal or command prompt and run the following command to install the create-react-app package globally:

npm install -g create-react-app

3 After installing create-react-app, you can create a new React app by running the following command:

create-react-app my-app

Replace "my-app" with the name you want to give your app. This will create a new React app in a folder with the same name.

4 Once the app is created, you can navigate to the app's directory by running the following command:

cd my-app

5 Now you can start the development server by running the following command:

npm start

This will launch a development server and open your app in the browser. You can start editing the code in the "src" folder and see the changes in real-time.

Congratulations, you have successfully installed React and created your first app!