Getting a Facebook App ID number

Hiya. I'm in the process of trying to get a Facebook App ID number (which is required to give my clients the option to log in through Facebook when they pay for items on my website). When I clicked on the link provided in the pay per view settings file, the link was broken. I've since found the Facebook developer page on my own (https://developers.facebook.com/products), but they offer multiple apps, and it's unclear exactly which one I need. One of the apps is called 'Login,' and I'm assuming this is the one I need, but would like some confirmation of this. Thanks for your time.

Cheers,
Aaron