Put OpenFeint or GameCenter in my iOS App

Many Games like 'Angry bird' have a 'OpenFeint' or 开发者_如何转开发'GameCenter' button. click it bring you to a page.

I want to use OpenFeint or GameCenter in my Game,how can I do it?

---

Download Openfeint and include GameKit in your game as well. And you can use both already..