Okay i downloaded gsnap you know the auto tune plugin. When i apply it to the song it auto tune the whole thing not just my voice the beat to which messed up the whole song. I want to know how to auto tune just my voice with gsnap.
GSnap does not fully work with Audacity because Audacity does not have MIDI input support.
If you have the voice on a separate track you can apply the GSnap effect to just that track by clicking above the Mute / Solo buttons of the voice track to select only the voice track.
From the GSnap Manual: http://www.gvst.co.uk/gsnap_manual.htm
It requires a monophonic input signal to operate.
If you have a stereo voice track, use Tracks > Stereo Track to Mono.
If you only have a stereo track with the voice and the beat mixed together, you can try isolating the voice, but this does not work on all tracks. See http://manual.audacityteam.org/o/man/tutorial_vocal_removal_and_isolation.html .
Audacity does not make GSnap, so we cannot help you how to use it.
There are some YouTube tutorials here you may want to look at, depending what you want to do:
You can also try AutoTalent instead of GSnap:
AutoTalent also expects a mono voice (or instrument) track to work on.
If you buy AutoTune or Melodyne they will give you technical support.