In order to configure Facebook, you must first create a Facebook app in order to obtain a Client ID and secret. You may do so at https://developers.facebook.com/apps.
Create an App
Click on Create App.
Select an app type of "Consumer" and click Continue.
Enter a name for your app and a contact email and then click "Create App ID".
Next, scroll to the bottom of this page and click on "Add Platform".
Then, find and click on "Website" in the box that pops up.
Enter your full web address (e.g. https://yoursite.com) into the "Site URL" field in the new "Website" box. Click "Save Changes".
Add Facebook Login
Click on "Add Product" in the sidebar under "Products".
Now click "Set Up" under "Facebook Login".
Next, click on "Settings" under the newly added "Facebook Login" product.
Now we will enter our OAuth redirect URI. This is simply the URL of your TML login page with the provider appended as a query argument. By default, this would be http://yoursite.com/login/?provider=facebook. Click "Save Changes" once you have entered this.
Request Advanced Access
Under "App Review" > "Permissions and Features", click on "Get Advanced Access" for "public_profile".
Once your access level for "public_profile" shows "Advanced Access", you're ready to turn your app on.
Turn Your App On
Obtain Client ID & Client Secret
Return to "Basic" under the "Settings" dropdown in the sidebar. Click "Show" next to "Client Secret". Copy and paste your Client ID and Client Secret into their corresponding fields in the TML Social settings.
Don't forget to check "Enable" and then click "Save Changes".
Login With Facebook
You will now see "Log in with Facebook" on your login form.