How to record add and save item in the file in angular?

I'm trying to use this example :

But I'm not getting it serious. That is, I enter data and save, but when I update the page undo the changes, and in the file does not add new items.

All the examples I tested happen the same. I think there is something missing authorizing the recording of data in the file, but I do not know what it is?

I do not know much about Angular .