The added elements are not commented in the event sheet.
I've had to add a "HP" instance variable to the Player object. It is not managed any further, that's up to you.
In this example Obstacle and Powerup objects are the only object you add. The damage quantity depends on the Sprite frame being displayed (3rd frame causes 150 damages/heals 150 HP whereas frame 1 only damages/cures 50).
This is a simple implementation example, but depending on your project and its specifications (would obstacles really require to be different object types ?) the implementation could be very different.