For new players I'd recommend watching ranked matches to see how the really good players play.
The game client stores replays of all ranked matches and it is available for viewing by everyone. Here is how you watch them:
First find a good ranked player's name, do this by clicking the League button (it is the last button to the right on the button menu, it looks like a shield). There on the side drop down choose platinum which will show leaderboard for platinum league-ers. After you have found a name, click the Profile button (looks like an msn messenger icon kindof), in the search field type in the person's name and click search, now you are looking at his profile. Click Recent matches and then click details icon for one of the ranked games. For Arena, ranked games are called Arena Challenge and for Conquest, Conquest Challenge. When you click the details icon it will show the endgame stats for that game, but additionally you have a button "View Replay" on the top next to the Match ID.
Buttons for camera controls in spectator mode should be in your keybinds.