Hey Op, I have your answer.
Try to get Fl studio. Autotune comes with it as a plugin called G-snap GJ, even with the demo so don't worry about it. Select T-pain effect under presets. After that, to make the autotune sound good and not off key after you sing or rap or whatever, you need to adjust the keys. You might have to adjust it, it also helps if you understand music... but you could always mess with the autotune.
You're welcome .