When the user uses the mouse to click on the screen I want to be able to print the coordinate of where they clicked to the screen.
You need to use a GUI such as lemur: Getting Started · jMonkeyEngine-Contributions/Lemur Wiki · GitHub
There are other alternatives; Nifty is the defacto standard for jMonkey, and I believe tonegodGUI has something of a following, though I’ve never used it.
“print” as in dump to the system console? Or?
“click on the screen” as in wherever the click whether they click no matter what is there?
“coordinates” as in 2D screen coordinates?
If all of those are “yes” then just register a RawInputListener with InputManager and whenever a mouse button is clicked then System.out.println() the mouse location in the event.