New and need help figuring out this site.

I am new here (kbin, but I guess this might post to other websites as well??) and am trying to understand how this place is similar and different from reddit. Is there a good overview somewhere? I already accidentally spammed this question three times as a microblog, whatever that is, and am trying to figure out how to actually do things.

How do I subscribe/join/whatever a community? Can I private message people?What terminology do I need to know?What’s up with the following people thing?How do the points work (agree/disagree, relevant/not relevant, something else…)?What else do I not know that I don’t know?

Thank you!