Farrago comes with a simple default sound set to show off what the app can do, but it's likely you'll want to make your own custom sound sets. You can create your own sounds and audio clips, even recording them with our own Audio Hijack, for use in Farrago. You can also use existing songs and other recordings with Farrago.
If you're looking for sound effects, sound artists around the world have made many sounds available for use. You can find millions of different effects by searching the web. Freesound.org has a massive database of tens of thousands of different sounds, while ZapSplat has a smaller library of tremendously high-quality audio. Check out these sites, and others like them, to find just what you need.
Note: Many sounds on the web royalty-free, but licenses vary, so be sure to check the license terms for any audio you wish to use.