Question: How does an h-bridge work? How do i control the motor with it? How can i stop the motor in it
Circuit Layout:

Explanation: A h-bridge is a classical solution to control a motor to go two ways, like forwards and backwards, left or right.
As switches you can use transistors.
As shown in the drawing in idle state all switches are open (1.) and no current goes (= motor is idle).
Once you close two switches in pair like in the figure 2. and 3. the current either goes the one or the other way through the motor, which results in the motor to rotate the one or the other way.
To stop the motor you have to short circuit the motor so the coils inside the motor consume the left current (4.). This will result in the stopping the motor more or less immediately.
(I have to look into the drawings.. there was something to protect the transistors)
marc: For protection you should put diodes across the transistors (cathode towards +).\\ Instead of separate transistors, you can also use h-bridge driver chips, which can be directly connected to a micro (arduino or other) and has just three lines for left, right and brake. also the protection is build in.