A Heads Up tournament consists of tables with two players per table. The players on each table play against each other (heads up) until a there is a winner. The winners then progress to further rounds to play more games until there is an overall winner.
The player who does not have the button is dealt the first playing card. The player on the dealer button is the small blind and the player not on the dealer button posts the big blind. The small blind acts first before the flop and last after the flop is dealt.
If number of player registered for a tournament is not 2, 4, 8, 16, 32, 64, 128, 256 or 512 some players will be given a bye for the first round.
The rounds will be conducted in a shootout style, with each round commencing at the same time and all players starting the next game at the same time.
Getting a read on your opponent is much more valuable Heads Up since you'll be playing every hand with him. Getting solid notes such as "over-bet pot with weak hand", "folds to raise" or "bet pot when checked to multiple times" will give you a huge edge in a game, assuming your opponent isn't observant to the same degree as you. Pay close attention, and adjust your game accordingly.
Since your opponents won't be completely unobserving, you should try to switch your game up and use your past play to your advantage, and to eliminate recognizable patterns in your game.