Installing ember-dialog tutorial

I am a relatively new user to ember and am finding it very difficult to learn. I am trying to use the following component. http://ift.tt/2g6a60v
the instructions are straight forward, they just dont explain how to call it as follows

const layoutName = "dialog/confirm";
const templateName = "messages/hello";
const promise = this.get("dialog").show(layoutName, templateName);

const yes = () => { console.log(`yes pressed`); };
const no = () => { console.log(`no pressed`); };

promise.then(yes, no);

They however seem to not tell you how or where to define "dialog". therefore this.get("dialog").show(layoutName, templateName) can never work. i have installed the component yet i still get a null;