You literally type in the domain on something like namecheap.com if it says available you click add to cart and click checkout. Familiarity with the process of buying something online is the only requisite. Everything after is the hard part.
And then it's just the small task of understanding DNS, TLS, HTTP, ip addresses, ports, VPS management, and security patches.
I can't say you need that to slap a domain on a site. Most good hosting services abstract that for you.