Creating an App for login via Facebook
In order to create an App you need to log onto Facebook at https://developers.facebook.com and log in with your Facebook account.
After logging in, it will be enough to enter in "My App" and click on "Add New App". Note that if you are not Facebook developers it will first need to make a short registration process.
During the new app creation you have to choose the type "www" (website), type a name for the new app, and then change the settings as shown in the following image:
In the "Display name" and "email contact" you can enter a name and email personalized, while the following fields will be set as:
-App Domains: mywifiservice.com
-site Url: http://mywifiservice.com
-Mobile Site Url: http://mywifiservice.com
At the end of the setup process you will have to make public the app by clicking on the Status and review and placing "Yes" flag in the upper right. There is no additional modifications or special settings.
To make sure that the login procedure via Facebook My Wi-Fi Service works with the newly created app (instead of the default one), we will just have to enter the App Id/App Secret in the Dashboard within the Captive Portal configuration of My Wi-Fi Service.