In order to "run" the web app, you need to turn your
/www folder into a web server. Again there are many methods to do this and people tend to stick with one or two ways to keep things simple. A few other options are unreliable such as Sublime Text's live watch package or static page generator (for example, Jekyll, Middleman App, and so on). They are slow to detect changes and may freeze your IDE so these won't be mentioned here.
The recommended method is to use the
ionic serve command line. It basically launches an HTTP server so you can open your app in a desktop browser.
$ cd HelloWorld_Sidemenu ...