How do I use "Audacity" a software for manipulating the pitch of a karaoke track?

I am curious as to how do experts manipulate the pitch of karaoke tracks so that a common man is able to render a song with equal ease as the actual artist? I would like to lower the scales of two tracks and am having a hard time comprehending the voluminous information about the usage of "Audacity" on the net. Can anyone guide me in a simplified manner?|||simply use vocador in audacity, or vocal remover option|||Audacity cannot be used to alter the key of an audio file. For this you would need software like Karaoke Sound Tools http://www.karaoke-software.net/karaoke-鈥?/a>|||Impossible.,