Have a gander at the latest articles, it shows you how to add the WPC app. Will be a very similar procedure for all apps I imagine. In essence, the toast bit needs to be added, also, go in to the battery saver bit and make sure background tasks are enabled, and banners are allowed. I have made a very poor explanation of it here, and I encourage you to refer to the article.
I did it with WPC, but it appeared not to show up at first. Ibhad to wait for it to get the first notification.