Take a quick look at how to start new game and choose allowed game options.

1. Choose "Game" > "New"
2. Choose who is playing (human vs. nouse, etc.,) from "Players" popup menu
3. In case that nouse is participating, choose nouse type from "Nouse" popup menu and press "Start" button.

Naive - least smart computer opponent. It does not check much for covering or attacking opponent pieces.
Agressive - smart enough, agressive nouse that allows to get to real fighting quite quickly.
Careful - most smart and careful computer opponent. It checks for everything including covered friend pices and moves to covered positions. It also takes into account distance to king, etc.
Note
It may be quite interesting to choose two nouse opponents playing against each other. In this case, game will start as soon as you press "Start" button. Note, that game may be paused. When paused, history menu becomes available and you may walk through it in order to learn more about position and nouse moves rationale.

In order to start playing, you have to select one of your pieces and choose a move from those shown in response. Then selected piece is moved to pointed position and game state is checked. Game state information is presented in main window title. Next move, important events such as check or pause are shown there. In cases that you can't select a piece or move, game will signal with stadard Mac sound. This is usually the case that you try to move in paused state or attempting to select a piece while two computer opponents play and game is not paused.

New game
New game window with allowed options. Easy to choose players and computer opponent type (if any). "Start" button or "Enter" key equivalent will start the game. And "Cancel" button or "Esc" key equivalent close the window.