Download a keyboard-to-piano bridge software such as Bome's Mouse Keyboard or KB piano. These programs transform the computer keyboard into a musical device. There is a trial version available from Bome's website. Install the program as instructed and launch it.
Left-click "MIDI-out" on the toolbar and select "Midi Yoke 1."
Launch Sonar and create a new MIDI track (click File select new track).
Click "MIDI input" on the right side of the track and select Channel 1.
Play the computer keyboard as you would a musical keyboard, experimenting with which buttons correspond to which notes or sounds.