Using create-react-native-app to start a new React Native project involves calling the create-react-native-app command, and passing in the name of the app as an argument. For example:

create-react-native-app my-project

This will result in the creation of a my-project directory. This is where you'll have all of the boilerplate code and other files that create-react-native-app takes care of creating for you. This is also where you'll find the node_modules directory where all of your dependencies are installed.

When you run this command, you'll see output that looks like this:

Creating a new React Native app in Chapter13/my-project.
Using package manager as npm with npm interface.
Installing packages. This might take a couple minutes.
Installing react-native-scripts...
+ react-native-scripts@1.14.0
added 442 packages from 477 contributors and audited 1178 packages in 19.128s
Installing dependencies using npm...
Success! Created my-project at Chapter13/my-project
Inside that directory, you can run several commands:
  npm start
    Starts the development server so you can open your app in the Expo
    app on your phone.
  npm run ios
    (Mac only, requires Xcode)
    Starts the development server and loads your app in an iOS simulator.
  npm run android
    (Requires Android build tools)
    Starts the development server and loads your app on a connected Android
    device or emulator.  
  npm test
    Starts the test runner.
  npm run eject
    Removes this tool and copies build dependencies, configuration files
    and scripts into the app directory. If you do this, you can’t go back!
We suggest that you begin by typing:
  cd my-project
  npm start
Happy hacking!

The output shows you what it's doing as it installs dependencies for you, and the commands that are ready for you to run right away. At this point, you're ready to launch your app.