Radio advert draft one

After sorting out a track and editing it so that it flowed I had to place it next to the voice over to see it the script was the right length, to accomplish this I had to shear the track with Itunes and open up another event on garage band one that is voice, I then imported the track, and began to record my voice to fit in with the time scale, this worked to an extent as I want to use a range of different voices to aim for my target audience and it was just mine, however it gave me a accurate time scale for my radio advert which at the moment lasts 28 seconds