Garageband. How do I remove the backing track and voice from my own recording

I am currently trying to do a project that involves recording my voice singing along with a backing track which I am using for timing purposes only.

I would like to be able to record my voice only and not the music or someone else singing.

The reason I need to do this is because there are several people doing this and it will be mixed into one version.

Everyone else who is doing this I understand they are using a program called audacity. I know that garageband has enormous capabilities but I just cannot work out how to do it.

I would so appreciate any help given.