WUnderground and OpenWeatherMap API keys are set in 'src/js/pebble-js-app.js'.
'web' directory goes on a web server. The URL to this folder is set in 'src/js/pebble-js-app.js'.
'web/keys.txt' contains purchase keys which you define. User enters purchase key in 'configurable_*.html' as presented by the Pebble app.
I've not tested this project as provided on GitHub since I no longer have all the Pebble tools. If you find problems please let me know.