Hi Tyler Ishikawa,
The backend endpoints are set by placing them in the /backend/routes/<endpoint> with a HTTP verb named js file to handle the Express.Js web server route. However, you won't have the authorization to view these services from outside of the Jive Instance that's has the add-on installed.
An example of a POST request to your your service URL's "test" endpoint would contain the file <integration name>/backend/routes/test/post.js
You would be able to send a post request to http://www.example.com/test
How you handle the incoming request (get/post/put/delete) for your service is just like any other Express endpoint setup.
I hope that helps you.
Correct me if I'm wrong, but a Jive-hosted add-on cannot include backend routes.