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.org/website/jekyll .
ID=$(docker run -d -v "$PWD:/src" -p 4000:4000 while42.org/website/jekyll serve -H 0.0.0.0)
docker logs -f $ID
Then browse http://0.0.0.0:4000/
Check