You don't need to add the codes for the Facebook Login to work, as it is a built-in feature in UWB Full. But, if you did want to, you could do it by 1) Copying/pasting it directly on the page itself by clicking on the HTML button on the Content Editor Box, on the Add/Edit page, or 2) Copying/pasting the code into an Ad(d) (using the Ad(d)s Manager), and then copying/pasting that generated Placeholder Text directly into the Content Editor Box on the Add/Edit page where you want it (directly on the box, you don't need to click on the HTML button in this method).
We can check out your setup for you further if you email a jpg attachment of a screenshot of your Facebook app settings. Also, please email your website admin panel url, username/password and we can check on your website admin panel settings for the Facebook social login. Please email this info again even if it has not changed from your account setup/previous emails.