You can undo right after you've added Auto-Tune to go back to the original file, but if you keep working in your project, at some point you won't be able to go back without undoing other things that you might want to keep. Please note that adding the Auto-Tune effect is a destructive operation, meaning that the effect will be printed to the audio file. OK, so now you're happy with your settings, just click Save and voilà! - you have successfully Auto-Tuned your vocals! If you're unsure what scale you're using, leave it at All notes (chromatic). You can also edit the scale manually by clicking on the notes in this dialog. The Scale control lets you select a musical scale.
Set it too Heavy for a very noticeable effect, or set it to Light for more subtle tuning jobs! The Amount control goes from Light to Heavy.
This opens up the Auto-Tune® effect dialog! Here you can choose the amount of the effect that you want to add and select a musical scale. So, you've recorded some vocals and now you want to add authentic Antares Auto-Tune® to them? No problem! Just hover over the region you wish to auto-tune, click EDIT (1) and choose Auto-Tune® (2).