Go to Site Settings > Google & Social Media > Meta Pixel
1. Follow Facebook's Guide to Setting up a Pixel.
2. When set up, copy your Pixel ID from Facebook Events Manager.
3. Turn on the "Enable Meta Pixel" button, paste your Pixel ID in the box, hit Apply, and publish your website again.
Your pixel, and Facebook Conversion Tracking, should then be working. You can test it with the "Meta Pixel Helper" Chrome extension if you wish.