One Signal notification on triggered event

I have been working on a chat app, all is going well. I can send notifications so I know some of the setup is correct. What I am having an issue with is sending a notification on a triggered event (when a condition is met) with the In-App messaging function on One Signal.

Key and Value - Where does One Signal look for these? I tried using firebase to store these values but no luck. My goal is to get notifications to send when a user posts a message.
Any ideas would be greatly appreciated.