How do you change your voice in video after effects?

i need a way to change thew way my voice sounds in a video/song. like if i wanted to make my voice sound demonic i could do it with this software... if you could please name softwares that dont cost anything? also if i can do this with windows movie maker and if u could tell me how to do this it would be great thank you|||You won%26#039;t be able to do it in WMM but either Audacity or Goldwave which are both FREE would do it.|||wavepad, its 30 day trial but works perfectly|||I would recommend exporting the audio and then editing it in a free audio program such as Audacity.