Please follow these simple step to register your app on facebook

1. Open Developer account from your Facebook.
2. Select "Create App" you'll be directed to a page where number of options will be available at the top bar.
3. One can reach there by just click "Create app" located at the left panel of your Facebook home page.
4. Clicking on Apps will open an option where user can "create a New App".
5. Once you select a New App then a view popsUp asking for basic info of app to be registered.
6. Once you are created an app successfully, your app is available but needs few amendments/changes.
7. Click on settings and enter relevant infos to app.
8. Make sure to click on "+Add Platform", If using for iOS.
9. After entering all info click save, here is an App Id that is to be used while coding for FB.
10. Now on status & Review make sure your app is public, the green symbol show that the app is public.
11. Click on Configure App Center Permissions fill all details.
12. Save and you have successfully created an app on Facebook.