Create an outline of the sounds you need. If you want quick, surprising music for sound effects, you might need several props. If you need music to build suspense or create an eerie environment, you will want a longer score.
Gather any objects you need for creating scary effects with the music. For example, a creaking door or the sound of footsteps approaching are classic sounds used to incite fear and anticipation. You can replicate the sound of thunder with metal pots. Use maracas for sinister rattling.
Compose any longer pieces of music you require. The key to making a scary musical tracks is, well, the key. Using notes and chords in a minor key gives a musical piece a haunting tone. You also can add an echo effect to the music.
Integrate technology for more experimentation. Download a free recording effects program such as Audacity (see Resources). Record your music or voice. Select "Audio Track Name" to name your file. Select the entire audio track so you can copy it. Select "Edit" and "Duplicate." Use the options under the "Effect" menu to adjust the pitch, add echo or adjust the speed of the track. Save your final recording and use the "File" menu to export your new scary music.
Add some quick sound files to your music. Hollow Hill (see Resources below) contains links to MIDI files that you can download for free. Your options include organ music, the sound of a bat attack and the musical themes from "The Shining" and "Tales From the Crypt."