Thank you! You should see a couple of buttons by each reply labeled "Helpful Answer" or "Correct Answer." Press "Helpful" for any and all replies that added to the discussion (they will earn their authors 5 points each.... you have a limit for how many you can award per message thread, but it's higher than the number of replies so far in this one). Press "Correct" for the one that was the ultimate answer. That will award 10 points and you can only do it once per question.
Welcome to gamification! 