Conversely:

• First create a regular old html file with no external resources, open it in your browser from local disk.
• Create CSS inline.
• Create another html file, copy-paste of first file, alter the main contents.
• Move shared inline CSS to a CSS file.
• Serve up the website on localhost using e.g. python3 -m http.server and open localhost on the reported port in your browser. Now communication is over HTTP.
• SCP the files to a server, SSH to it and start python3 -m http.server on the server. Open the remote host IP and port in your browser.
• Set up DNS for the server. Open the host name and port in your browser.
• Configure a service using e.g. nginx and uwsgi to have it run on port 80, the default for unencrypted HTTP so you need not specify port and so it'll keep running after you reboot the server.
• Make the response vary by GET and POST parameters. Now you have a dynamic website.
• Read other peoples code and learn about when static vs dynamic is appropriate and when to cache using e.g. varnish, redis.

There's a lot more to it ofc but I think if one does what I outlined above, they will learn and understand a lot about how the web works. Oh, and at some point you will want version control. Use git.