Hello and Welcome to Programming Puzzles and Code Golf! I'm delighted that you'd like you join our community. We're glad to have you.
To get a feel for the community and how to contribute:
You can start with the Tour, which to be honest isn't terribly informative, but it's a start.
Check out the Help Center for more details on what kind of challenges and submissions are acceptable.
Take a look around the site and see how people do things. That, in my opinion, is the easiest way to get a feel for the community. It sounds like you've already been doing that, which is great!
I recommend trying your hand at answering a couple challenges and if you feel like writing your own, you can post it to the Sandbox where you can get feedback on it before it goes to the main site.
If you come across challenges that you don't understand immediately, don't fret! Often others will have the same questions. In that case you can leave a comment on the post asking for clarification. Challenges should contain sufficient detail so that a broad range of people can participate. Sometimes the subject matter is highly specialized, often pertaining to advanced mathematics, but if that's not your forte then we have plenty of other challenges to choose from.
If you have any further questions along the way, you've already found the perfect place to ask them: Meta!