Can't get UI to work - google-apps-script

Question

I am trying to learn the UI Service in order to build my own form (panel). I tried copying and running the example panel, but I can't get it to work (the code is below). The panel will not pop up. Do I have to set something in my browser? Please help.
function doGet() {
// A script with a user interface that is published as a web app
// must contain a doGet(e) function.
// Create the UiInstance object myapp and set the title text
var myapp = UiApp.createApplication().setTitle('Here is the title bar');
// Create a button called mybutton and set the button text
var mybutton = myapp.createButton('Here is a button');
// Create a vertical panel called mypanel and add it to myapp
var mypanel = myapp.createVerticalPanel();
// Add mybutton to mypanel
mypanel.add(mybutton);
// Add my panel to myapp
myapp.add(mypanel);
// return myapp to display the UiInstance object and all elements associated with it.
return myapp;
}

Answer 1

The doGet() function runs when the URL of your App is either first loaded in the browser, OR you refresh the page in your browser. If your App is a Stand Alone App (Not attached to a Sheet or a Doc) then you will have a file associated with that app in your Google Drive. The Apps Script file icon is a blue square with a white arrow pointing to the right.
If you double click that file, it should open up in your browser and run the doGet() function. You can also provide the URL of the App as a link.
But first you need to deploy it.
Click the icon of a cloud with an up arrow in it:
You'll be asked to name your project if you haven't done that already. Then, you'll get a pop up that looks like this:
Click Deploy
You'll get another pop up, . . . click 'Latest Code'. Your app will open up in the browser.
The code you supplied puts a button in the window labeled, 'Here is a Button'.