Hi Ordnance,
Thanks for reaching out and welcome to Netlify’s Support Forums!
You can add a domain by following Netlify docs here:
The Netlify site you mentioned doesn’t seem to exist, but if it did you would go here:
https://app.netlify.com/sites/kenmortar/domain-management
There you would see the Production domain section and you would click on the Add a domain button.
We have a Support Guide to help with setting up DNS here:
It’s important to note that you’ll either configure External DNS or Netlify DNS, not both at the same time.
To help you decide whether to use External DNS or Netlify DNS, please refer to this Support Guide.