The "Hello Word" SuiteScript example

I am having trouble getting a standard example from the online documentation to work.  The documentation for server-side Suitescript gives a simple js example to say 'Hello World', and I am just trying to get this to work!

However, I am not sure what to do with the js code file. I have uploaded it to my NS account as required, but the dodumentation doesn't tell me what to expect next. Is it that I should be able to click a button and have the code executed server-side, with return of html to the browser? If so, how do I associated the code file with the button? If not, then what is supposed to happen?