How do you set up a web server on Mac?

What Mac model/year/OS do you have?

If this will be a publicly accessible server, use a web hosting service rather than doing it on your computer.

Here is a good article: Setting up a local web server on a Mac - Apple Community

Typically you need a business internet account to operate a public-facing webserver. You provider can tell if you have one by the traffic to your public IP address.