Customize the widget using the provided interface and click 'Get Code' when you have finished making your tweaks. This will open a dialog box.
The dialog box will show you two pieces of code:
The code for your plugin that displays the widget on your page
For Name type 'Facebook Widget', for Placement choose 'After Body Tag'. Then paste in the script and replace the field APP_ID with your App ID from Step A.
Next, copy the plugin code that displays your widget and paste it onto your Unbounce landing page as a custom HTML component. To do this, drag the the Custom HTML widget onto your page and paste the code into the dialog box. Click 'Done. You can then position and resize the placeholder box on your page as need be.
That's it! You are now ready to save, preview, and ultimately publish your page.