It doesn't get more simple than this very short simple presentation. This is a very good start! If you want to learn more about this topic, you can find many resources about digital citizenship under "DML" in my tags. I used DML to stand for Digital Media Literacy. I have some other resources under "Participation" that may relate in many cases.
Boiling digital citizenship down for easy digestion (7 slides + an addendum with some research background).
Via Dave Webb, John Boone, Ken Morrison, Sandra Mason