Voice recording with Cubase elements 8

So I’ve desperately been trying to record my own vocals on an instrumental track but it’s not working properly. I imported the instrumental track and then added a new track to record my voice. However, when i try to record my voice, it records both my voice and the instrumental. Because of this i’m not able to make any volume adjustments between my voice and the background music. I tried this with garageband too and had the same problem… I’m using the UR12 audio interface. If someone could please give me an idea of what I’m doing wrong that would be great!