1. Install the dependencies. The dependencies are included in the package.json file, you just need to install them:

$ npm install

2. Start the development environment To start the development environment in gatsby is quite easy, you just need to run this command to start it up:

$ gatsby develop # for people who installed the gatsby-cli
$ npm run develop # for people who didn't installed the gatsby-cli

These commands should have your site running in http://localhost:8000. Edit the files and it should update in real time.

If the commands above don't run or don't function as they should, then consult to this command below:

$ gatsby develop -H 0.0.0.0

The prerequisite to run this command is to install the gatsby-cli:

$ npm install -g gatsby-cli