Want to add french version to the website and trouble in lauching it due to 'index.html'

1. I want to add a drop-down so that people can see the French version of my website.
2. When I double-click the ‘index.html’ file, it works fine from the local computer, but I’m having trouble hosting it on GitHub. Here is the link to the repository- https://github.com/Kkhurana007/blog_le07decembre.github.io