To use the accelerometer (or any sensor in general) your class should implement the SensorEventListener interface, or you could do anonymous inner classes for them. To access the accelerometer you will need to get the SystemManager from the system and get a sensors list from that.

myManager = (SensorManager)getSystemService(Context.SENSOR_SERVICE);
// this will return a list of Sensor
sensors = myManager.getSensorList(Sensor.TYPE_ACCELEROMETER);

From the sensors list then select the first element, this should be the accelerometer sensor.
The parameter of the event listener is a SensorEvent. From this event you can access the x, y, and z values of the accelerometer and do with them what you want.

calculateSomething(event.values[0], event.values[1], event.values[2]);