Honestly reddit.com/r/usenet was the best but we know how that’s going. You can web search but basically you pay for a provider, sign up for indexers who are like torrent trackers and provide .nzb files. You use either SABnzbd or NZBGet to download the actual files. Sonarr and Radarr are automation tools. There’s some other concepts like retention and backbones but that’s not as important to get started.
https://frugalusenet.com/ is a good provider to get started. https://www.nzbgeek.info/ and https://nzbplanet.net/ are good indexers for beginners. I recommend SABnzbd over NZBGet as I don’t think get is actively being developed for anymore.
https://trash-guides.info/ is very good for Sonarr/Radarr set up but it can be quite overwhelming for non-technical users or beginners.
I also just remembered cache exists so poke around https://webcache.googleusercontent.com/search?q=cache:ZU9NxnpPelwJ:https://www.reddit.com/r/usenet/wiki/faq/&cd=10&hl=en&ct=clnk&gl=us
I remember a Reddit post talking about how predatory this game was