I love ice hockey but just started watching last season. I don't understand it all yet. 
I see, well its a simple game really. Two teams compete to shoot a rubber puck into the opponent's goal to score points!
That does sound easy. How do they get a penalty? I have seen people go to the box but unsure why. 
Its due to foul play by the opposition, sometimes when a move is seem as being too fast-paced and physical, the referee gives a penalty!