To get auto tune to work in audacity you must follow these steps..

http://www.audacityteam.org/vst/ go there and download the plugin..

Install it and restart audacity. Look in the effects menu and autotune should be there

To get the t-pain effect.. set your auto tune to these settings

key = c scale = major retune speed = 0 scale detune = 4 cents, 441.0 hertz humanize = 0 natural vibrato = 0.0

now whats most important rate = .1 onset delay = 0 variation = 0 onset rate = 0 pitch amount = 0 amplitude amount =30 formant amount = 100

messing around with audacity...its a little different setting i think... (my old setting were used in sony acid)

To get the t-pain effect.. set your auto tune to these settings

key = c scale = major retune speed = 0 scale detune = .04 cents, 441.0 hertz humanize = 0 natural vibrato = 0.0

now whats most important rate = .1 onset delay = 0 variation = 0 onset rate = 0 pitch amount = 0 amplitude amount =.3 formant amount = 1