This isn't rocket science. The linked document takes all of 10 minutes to read and understand. If that is not enough, there are three years worth of WWDC sessions on memory management available on iTunes U (this year's are even free!). It's something as basic as learning a new language's if/else structure.

For reference, I'm a five year Java dev who has now been doing iOS dev for two years, and had no problem switching from GC to manual memory management.