Download the free demo. (Note: Win 32-bit only; Windows 8 may not work.)  

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Video: Up and Running in 3 minutes

If you use own music software like Propellerhead's Reason or Record, Ableton Live other any other sequencer/DAW with built-in synthesis or sample-playback, you can use a midi router like Midi Yoke to route the midi output of Sounder into the synth. The midi notes that Sounder sends out will go to your synth of choice, which you can then treat with reverb, echo or other effects for truly wonderful atmoshpheric ambient music. The possibilities are endless.

If you press "record" in that program's sequencer, you can save the music you've created into a retrievable MIDI sequence, which you could edit or manipulate from there.