Thank you very much! I actually found the documentation for Lemmy. It explained and answered all my questions (for the moment). Feeling kinda stupid for posting this; makes me want to delete it 😅.
Just joined Lemmy today. From what I understand, there are different Lemmy instances that host different communities. I supposed that to interact in a community hosted in a certain instance, I would need to create an account for that instance. Ended up creating 10 different accounts.