Just clone, modify and push.
To test locally, either you know your way with ruby and have the env installed, or use docker to serve it:
docker build -t while42/web .
docker run -d -v "$PWD:/src" -p 4000:4000 while42/web serve -H 0.0.0.0
docker logs -f <container_id>
Then browse http://0.0.0.0:4000/w42-proto/
Check