What’s the most user-friendly guide to get this set up on a domain you own? 

 https://jb55.com/.well-known/nostr.json 

 you can use https://damus.io/key/ to convert your npub to hex 

 I followed this guide, it was very easy to do.

https://nostr.how/en/guides/get-verified  

 🙌🏻 👍