I DO think you can get a plugin for Audacity which will autotune the sound, but the plugin itself may not be free. Audacity doesn't do that alone.
Quote by AA00P
Listen to the man, he's Jewish.
suggest you "acquire" a copy of Adobe Audition which comes with a pretty nice autotune effect or "acquire" the Autotune plugin itself which should work with Audacity too.

btw Audition and Audacity are way too similar names considering they do the same sort of thing, think Adobe did that shit on purpose?
Reaper has a built-in autotune effect which actually works pretty well and hiding small mistakes

you can analyse pitch with Audacity though, select the note and click Analyse -> Plot Spectrum, put the size up as far as it will go and change the axis to logarithmic and you can easily see what frequencies and notes are present