You do not have to care about the Template ID, don't fill it in. (it is used if you set up several in the app config file, it is nothing for you to care about though). (And since you obviously don't understand the data field either, don't populate it)
You can only send one update per session, the others will not be sent. The Sprite you want to share must be placed on the layout.
If the text will show or not is dependent on the platform and changes for time to time. You can leave it, currently FB only seem to post image though (IIRC they said it was due to GDPR)
Your green button is not for sending any message, it is just for switching context, verify that the context is actually changing, otherwise the next event will not fire.
I don't know what your restart function do, so hard to tell. if you restart the game or something then the change context event will not be fired either..