@interstellarnik what I've learned so far: the house is your personal feed which shows the stuff from people you follow, the bell is notifications about things relating to you, the two little guys is the federated feed, which is posts from anyone in this instance, and then the globe is the public feed, which is like every instance that this one is affiliated with (or something?).
Otherwise you just post things to your heart's content and follow people you like and who post stuff you like