When you setting up Social Member Lock and want to allow your users to connect with Facebook for your Social Membership, then you need to create a Facebook App and enter its details in to the setting page as shown in the image below:
*This Step is required before you can use Facebook for your Social Membership.
Go to the Creating A Facebook Application Knowledge Base page to see a complete step by step tutorial on how to create an Application for Facebook and enter then the Facebook App ID/API Key and Facebook App Secret in to the specific settings.
Facebook API Local: Here you can select the language of your website. Facebook will use this setting to display the Facebook messages in the chosen language.
Redirect URL: Enter an URL of your website to which users, who didn't grant all the asked permissions to your Facebook App, get redirected. This could be an extra page, where you explain why they have been redirected and where you could ask the user to connect with your app with granting all the asked permissions to be able to see the locked content and to get all the benefits of the Social Membership.
Login Redirect URL: After users have connected with your app, you have the ability to redirect them to a specific page, such as a members page for example. If you just want to display the hidden content and want the user being redirected to the page where he used the Facebook connect, then leave that empty.
Birthday Message: Within this option, you have the ability to enter a Birthday Message, which will then be sent to the connected Facebook users on their Birthday. This will automatically be done every year, as long as they remain connected with your Facebook Application.
Note: When you check that on an user's timeline, if the Birthday message has been posted, then it can be, that you don't see that message. This depends on the permissions the user gave. They have the ability to display all the message, which are being posted on their wall, to be seen only by them self, by their friends or by the public. So if they have set that to only me, then you can't see any messages at all.