Here the trick is not necessarily to sell your music. While that would be a good thing. What I'm talking about now is shear exposure.
I've made ads on ebay that draw a lot of page views, but don't necessarily sell. Sometimes a title that will draw attention, and pricing that will draw attention, is not necessarily good for making the item sell. That's just the way it is.
When making an ad to sell, I make an ad to tell. When making an ad for exposure, I don't necessarily worry about selling my music. Don't forget each page view is that much more exposure.
In your ad, you can talk about yourself or your group, and you can talk about your music all you like. You can even put a link to download a short sample mp3. It's all up to you.