Well the biggest thing is learning how to scout in game and in turn this will help you learn the various leagues around the world. Hockey has a very complicated development system that is almost global in scope. At least this is where I'll start.
In Canada we call our development system Junior Hockey. It consist of 4 levels. Major Junior, Junior A, Junior B and Junior C. Major Junior is headed by the CHL(Canadian Hockey League), a body that runs 3 leagues, the WHL (Western Hockey League), OHL (Ontario Hockey League) and the QMJHL (Quebec Major Junior Hockey League). Junior A is headed by the CJHL (Canadian Junior Hockey League) consists of a league in every province. Most higher level players will never play below those two levels.
The American's have an equivalent but instead of Junior they have a Tier system.They call their top leagues Tier 1. The USHL is the only Tier 1 league in the US governed by Hockey USA. It is a direct feeder league to the NCAA, I'll assume you are familiar with that because of your Royals avatar.
The Europeans have much more complicated systems.We'll leave those for another lesson though.
I'd say read up on those two systems first through wikipedia.
Here is a picture that shows the levels. Please feel free to ask any questions and I will try to answer them as best I can.
