Where can I find MIDI files of songs I want to play or practice?
While our software does not convert audio (wav, mp3, ogg, flac, etc.) files to sheet music, it does transcribe MIDI (.mid) files to sheet music.
There are a lot of great .mid files out there of songs done by musicians who are dedicated to creating faithful recreations of many, many thousands of songs. You can use your favorite web browser and search for "MIDI songname" where "songname" is the title of the song you're looking for.
You can also peruse through the MIDI File Directory at http://www.beanfieldcastle.net/MIDI_Directory.html
as a good place to start, especially if you just want to get some good files to begin using Notation Musician or Notation Composer.