Reading from another Magento stack overflow thread, everything seems pretty straightforward. Found here: How to add new facebook tracking pixel to magento site?
My question is for this one:
fbq('track', 'CompleteRegistration');
This can be done as part of your event or observer using customer_register_success
event
Does this mean I can throw a <script>fbq('track', 'CompleteRegistration');</script>
into that page or I actually have to integrate it into observer method?