Using Java Program as part of Java Web APP

I have built a java program that does very simple reading, storing, and processing of server side data that it receives from some electronic sensors. This information now needs to be put onto a webpage.

Some calculations need to be done server side so I want to keep the Processing done in java rather than an interpretative language like javascript or python.

Anyway How do I get the information from the java program up onto a website using a java web application? I am a little unfamiliar with JSP and Servlets though they aren't too complicated I do not know how to get my current working program to work with those and print out the server side information.

It doesn't need to be anything fancy this is just a simple program to do some real time remote monitoring over the web of some electronics.

I do know and understand HTML as well so i do know how to work with those.