If you’re able to post here, you already know most about-it,

You subscribe to communities, post content, and comment-it, you can upvote the content and sometimes downvote it, as easy-as-it.

Regarding the federation, here is an explication for Mastodon but it also applies to here https://tilvids.com/w/887e7b95-a6b1-4df1-83fd-d5c47f17ec4c