Get the clearest recording you can, with the target sound isolated from other sounds, and with a half-second or more of typical background noise at the beginning of the recording (and it works best with live birds outdoors, not so well with playback of recorded sounds indoors).
Use the Isolate Song interface to draw a tight box around a short phrase of the song you are interested in. This filters out any extraneous noise that would otherwise confuse the app.
Shorter recordings are actually better than long (but you can make a long recording and isolate a short section of it).
It's a collaboration between you and the app. Don't expect perfect accuracy on the first try, and remember that the app does not attempt to identify short chips and squeaks.
Enjoy it, learn from it, and let us know how it's working.