Hi. Have you created some type of management system for your stats? First you will need to create a management system using playmaker and then create the specific conditions for it to occur.
Maybe first start by making some float variables on your character to hold the states. Strength, health, etc. Then you need to decide what conditions will change these stats.
For example, each time you kill an enemy, maybe the player needs to get +0.1 to the strength (or experience).