First, copy config/local.json.example to config/local.json and change the values if necessary.
Make sure you have npm installed. Then, execute:
npm install
This will build the assets and place them in dist/ folder. To build them manually, execute:
npm run webpack
Or, if you have webpack installed globally, just:
webpack
For local development, watch mode may come in handy:
npm run webpack-watch
or:
webpack --watch