A:
Great questions! iTrip is an FM transmitter, which means that it transmits a low-power FM radio frequency that your car stereo can receive. For best results, though, you need to find a frequency on your car stereo that doesn't have any music or audio on it, one that's all static. This means that there are no licensed broadcasts on that frequency that iTrip will have to compete with. Your best bet is to find three staticky stations in a row, then tune to the frequency in the middle of those three.
As long as you're just driving in town, you won't have to repeat this process each time you use iTrip. If you're traveling more than 50 miles out of town, though, you might have to retune iTrip from time to time.
Hope that helps! ^MS