Phaser comes with a comprehensive suite of examples. At the current count over 160 of them. Whenever we add a new feature into Phaser we create an example to demonstrate how to use it. They are short self-contained snippets of code that focus on just a couple of elements and nothing more, and as such they're really useful to learn from!
Although we've uploaded the Examples to our site, we still recommend that you copy the whole phaser folder (the entire repository) to your webroot, so you can easily run the Example browser locally.