I assume you mean, how do you aim with the bow ? It's a fairly simple concept reminiscent of the old Light Guns for PlayStation and arcades, and even the NES. Basically, all you have to do, is put the sensor at the bottom or the top of your TV. Then just aim the Wii-mote at the screen.
To answer your second question: No. Not all games will use this system. It's mainly for first or third person shooters, or any type of shooting game. You can also use it for example, in some games like Wario Ware Smooth Moves, though most other games make more use of the motion sensor than the aiming.