See How It Flies Is a useful resource. Take a look at chapter 1 to clear up the differences between power and energy
But don't get obsessed by this small aspect of your flying, as long as you know that climbing at a lower airspeed than that for optimum rate of climb will cover less ground during the climb thus give you a steeper angle (despite the somewhat poorer rate of climb) For most light aircraft it doesn't make a lot of difference, much less than a few knots of headwind!
But what do you mean with:"The more power wasted on the atmosphere, the slower you go up."
I think he is saying the more induced drag you create, the slower you go up. Just another way of putting it......