To install React, follow the instructions on GitHub.
If you can see this, React is not working right.
If you checked out the source from GitHub make sure to run grunt.
This is written with JSX in a CommonJS module and precompiled to vanilla JS by navigating to the example directory
cd /path/to/react/examples/example-nameand running
npm start
npm install
Learn more about React at facebook.github.io/react.