Install a free recording program. The Internet offers numerous free multi-tracking programs that allow you to create custom beats one instrument (or layer) at a time. Choose a program that lists "MIDI" and "multi-tracking" among its specifications.
Connect a MIDI keyboard to your computer if you own one. Otherwise, you can download a program that turns your PC keyboard into a MIDI instrument, such as MidiKeys or MIDI-OX. While this software runs, the keys on your PC keyboard will correspond to notes.
Open your recording software and set up your song. Most DJ songs use tempos between 130 and 140 beats per minute, so select a number in this range for your "tempo." The tempo box usually appears along the very top or bottom of the project window.
Create a new MIDI track (this option should appear beneath your menu bar) and locate your software instruments. A typical DJ song relies exclusively on synthesizer sounds and samples, so open your "virtual instruments," "software instruments" or "MIDI instruments" (sometimes accessed from the menu bar) and locate your synthesizer sounds, such as techno drum kits, electronic drum kits, synth leads, synth bass, pads and fx.
Select an electronic drum kit from your list of software instruments. Open your MIDI control program, or connect your MIDI keyboard, and begin playing keys to discover which keys correspond to which notes. Take a moment to familiarize yourself with the layout.
Click "Record" with your first track highlighted. Your track will look like a horizontal bar stretching across your screen. After pressing "Record," begin recording an electronic drum sequence. Press "Stop" when you finish.
Create a second track by selecting an electronic bass instrument from your virtual instruments and record an electronic bass line. For a trance-like effect, you can add a slight echo to your bass line, using the options on your "Effects" menu.
Create a third track for your melody. If you want to go for a simple drum and bass, you can just add a few sound effects; experiment with your digital effects and save your song. If you want to create a trance, ambient or other melodic piece, choose a "Synth Lead" from your virtual instruments and create a melody line (or multiple melody lines).
Add samples (loops) to fill in any gaps or add extra dimensions to your track. You can download samples from free loop websites like Free-Loops, Looperman or Loopasonic and drag them directly onto your project window onto their own tracks. If you cannot achieve a good sound using your virtual instruments, you can piece songs together just using samples.