JAVA REST API Call From Web App

I have somewhat of a general question and this seemed like the best place to ask!

I have been through the JAVA API with Spring on Codecademy and am now wanting to attempt creating my own REST API with Java and use it on a web application.

The web application is going to be built using HTML (just a simple budgeting tool), but I would like to use Java for the backend / API.

I know there is a course on Codecademy for connecting the front and back ends, but this is using javascript, and I have been unable to find hardly ANY useful info online.

Can you PLEASE direct me to a portion of Codecademy or another reliable source that discusses making calls to a Java REST API from a web app.

From the little that I have seen it looks like it can be done using javascript within the HTML page (or maybe using HTML directly, I am not sure because I have been able to find so little information).

So ANY help with this would be GREATLY appreciated!

Thank you,