Welcome!

I like to share these two guide pages because I find that people like the infographics:

What is the Fediverse (which includes Lemmy) and how it works: https://fedecan.ca/en/guide/get-started

How Lemmy specifically works (ex. where are the communities, where are the users): https://fedecan.ca/en/guide/lemmy/for-users/detailed-overview

Hopefully these guides are helpful, alongside all the other great advice people have shared :)