Welcome newbie. Most of us were in your shoes recently. You’re already following the top tip: be engaged. To be counted as an active user you need to comment or post once a day. Nothing wrong with not being active, but the number of active users is a shiny sparkly number we’re all staring intently at for the moment.
If you are looking for the communities similar to Reddit, look at sub.rehab. You can filter that to just lemmy and kbin.
Enjoy. Your task now is to find the poop post. You’ll probably catch references to it soon, if you haven’t already.