Combine your electronic music tracks into one stereo track. Exporting the audio sequencer file as a WAV file will simplify this process. Go to the "File" menu and select "Export" or a similar command on your program. Save the file as a WAV file and press "OK."
Select the "File" menu and choose "New" from the drop-down menu. Drag the WAV file you created from Step 1 into the audio editing pane.
Hook up a microphone, preferably a cardioid vocal microphone, to the mic output of your computer's sound card. This can be found along the left side of most laptops, or on the front, and sometimes, the rear of a computer tower.
Press the red circular "Record" button and a new track will appear and start recording your vocals. Let the singer listen through headphones as the audio file plays back. She will sing the vocal part on top of this track in real-time.
Export the file as a WAV file again and enjoy your new electronica song with vocals.