Hallo
You will receive some notification if you click on the Button of subscribe. Some notification are information from your office.
Once you've subscribed your user, you'd send their subscription to your server to store in a database so that when you want to send a message you can lookup the subscription and send a message to it.
To simplify things for this code lab copy the following details into the Push Companion Site and it'll send a push message for you, using the application server keys on the site - so make sure they match.