Install your music notation program and set up a default score. Notation programs will ask you to select the type of score you want when you start the application. For now, just select a single treble clef staff.
Select the "MIDI/Audio" menu and select the "Instrument List" option from the drop-down menu.
Choose the musical instrument you would like to play back. There are 128 general MIDI options, ranging from traditional violins to gun shots and helicopters. MIDI is a standardized platform for creating music. For instance, general MIDI instrument one, will always be an acoustic grand piano.
Enter the notes into the score to create a playback file that will allow you to create your background music. Press the playback option to hear the music played back. If you don't like what you hear, drag the notes in the score up or down to change the pitch to the correct note.
Create more complicated background music by adding several new staves to the file. Each staff can have its own sound.