How to create a website in N language?

Question

FastCGI

Let's say there is a language N. Some new one, for which there are no libraries, although there are the most basic ones. And there is the FastCGI protocol. How to create a site in this N language and FastCGI? What does this even mean? Does it mean writing a module for apache or nginx in that language, ? If yes, how to do it? I want to do all this at a low level and on my own.