This has aged and things like signing up to snort first and getting an Alby wallet aren't necessary any longer. But, here you go.
nostr:naddr1qvzqqqr4gupzqmn477tj8972x227pax2p77xawwv0xlgtwha644ax7pzpj5wae6wqq8h5ctswd68yetpd5kkwatfv3jsfnjvg5
TLDR:
* Log-on to zap.stream
* Head to the dashboard - https://zap.stream/dashboard
* Grab your stream url and stream key fron that page
* Setup stream details (name, tags, category, thumbnail.
* Put stream key and url into OBS (or owncast, shosho)
* Go live.
If you need more help, zap.stream has a discord and a NIP-29 nostr group.