First of all you must be using beta 3 or newer to use the extensions for them, second you need to create an app on both Facebook Developers which you need a mobile phone linked to your account now, as for Twitter you need to go to Twitter Apps and create a app, I'm not sure if they've updated it so it requires mobile phone or not, but to be safe you should add on on your Twitter account. After all that's done all you need to do is enabled the extensions from the extensions tab in the admin panel and place the App IDs each App's provider into the extensions settings.
