I have attached an updated version. There were a few things wrong:
1) SInce "health" is a member attribute of the player, you need to say "player.health" not just "health".
2) Your timer was also called "health". I renamed it "healthTimer".
3) Your "you lost" message was outside the "if". It's now inside.
4) DecreaseHealth decreases the player health by the amount you give it. Since you passed -1, it decreased it by -1... which actually increased it by 1. I changed it to DecreaseHealth(1) to have it decrease by 1 each time.
You have it set up as a timer, with a period of 2 seconds. If you want the health to decrease on each turn, then you should set up a turn script instead.