From February 2012 onwards, Facebook stops App profile pages. But you can still move all your page likes and users to new page (till Feb).

The new Facebook app creation flow is really confusing.

For developers, to add a app as a tab to another page, youneed to user the following URL:

https://www.facebook.com/dialog/pagetab?appid=YOURAPPID&next=YOURURL

next parameter should be your canvas page url.

Here you can see an option to add this app to your page.