To find a specific Action within the app, use the Search bar in the top of the app screen. You can search by Pin name if you know it, or use any keywords related to the action you're looking for. If it is an action you have recently logged, look no further than the Recent category from the Home screen. (The Recent category icon resembles a clock.)
If you've come up with a new Action you want to share, log it with the Sustainability Action -- find it with Search.