How can I "join the conversation"?

Honestly, I don't know how I can join the conversation online, especially since I don't even know what the conversation is really even about. It really depends on what the conversation would be. I don't really pay attention to what I am deeply interested in because I don't really care. If I like something, then I will almost certainly get involved in it. Sometimes my interest wanes, other times it never seems to be satiated. I have found so many different things to be entertained by that I no longer want or need to keep track.