You need to get an audio file of no more than 5 seconds long, so probably just an mp3, and convert it to .wav.
There are alot of sites where you can do it, this is the top google search result: http://audio.online-convert.com/convert-to-wav
Never used it, but I guess it should work. Just upload the sound you want as a kiai sound and this will convert it to .wav, making you able to upload it to toribash.