I got a physical server at home and I want to do the following silly project to learn the concept behind server-backend development, and then do a real project later on:

• Idea: Turn the server to a calculator. I want any person publicly send a query to the server (i.e., 2+2) from the terminal and the server give me the result.

So the question is basically where to start, what sort of software I need to install, and what sort of program I need to write?.