If you're new to fedi/lemmy, welcome! We hope you enjoy your stay.
If you've used Reddit or another similar platform, Lemmy should about the same. Federation, mostly when discovering content your instance hasnt seen, is a bit more finnicky. https://lemmyverse.net/communities is a useful tool for discovering content, if you wsnt to check everywhere for something. That bottom link with the exclamation mark is the one to copy in your instance's search, as itll discover the community that way if you can't see it otherwise.
also, pro tip: sort by top 6 hours. Youll thank me later.