Welcome!
I would recommend browsing our road map first. http://thrivegame.wikidot.com/releases-roadmap
If you do find something you wanna work on check to see if anyone else is already making progress on it and get with them to see how you can help.
Also a lot more discussion is on slack. However because of timezones it can be hard to get feedback when you want it. I have it on my computer and the app on my phone so I can check it on breaks at work.