heart stone help

On a minion card, there are two numbers on the bottom. What are these and how come every time I attack the enemy minion, i lose my card?

 

The left is your "power", basically how much damage the minion can deal. The right is your "health", how much damage it can take before dying. If health goes to 0, the minion dies.

You're losing your minion every time because it's a 1/1 attacking a 1/2. It's dealing 1 damage and taking 1 damage. Leaving the enemy at 1/1 and your minion at 1/0 (dead).