Download a free or open-source audio recording program. Depending on your personal needs and operating system, you might explore a program like Audacity, Ardour or QTractor. Many options are available, so download and tinker with a variety of programs if you cannot make up your mind at first.
Set up your music equipment. If you have a USB mixer, audio interface, a microphone or even just a guitar at your disposal, you can get right to work. If you have no instruments or no knowledge of how to play an instrument, fret not. Sites like Looperman, Free Loops and Loopasonic provide web surfers with legal, royalty-free audio loops (samples of different instruments that you can layer together for music mixing) that cost nothing to download and use. Just look for loops pertaining to the types of instruments that fit your style.
Record your music. When you open your recording software, you should notice a tool bar along the top of your screen, and below that you should notice a rectangular time line (measuring the seconds of your song project), and below that you may notice a series of horizontal bars (or just one bar, if your program does not support multi-tracking). The bars are designed to contain your recordings, which will appear as shaded, rectangular regions with wavy lines. To record, click the "Record" button, which may look like a red dot or a letter "R."
Record additional layers by adding tracks. If your program includes a multi-track layout, you can layer your music by adding new horizontal bars below the first. For example, if you recorded yourself playing guitar on the first track, you can select "New Track" from your menu bar and then record yourself singing on top of the guitar, for a multi-layered recording. Keep adding tracks to contribute all of the layers that you need.
Add your audio loops. If you have no instruments, you can drop your previously downloaded samples onto the project window and use them in place of live instrumentation. Just drag the loop files onto the blank horizontal track spaces and arrange them however you want them to appear on the time line. Layer your loops exactly as you would layer live recordings -- for instance with a guitar loop directly on top of a drum loop, for a combination of percussion and melody.
Mix your tracks using the options provided on your main window space, tool bar and effects menu. The effects menu contains principle audio effects like reverb, tremolo and delay, and may appear automatically on your software window, or may appear on your menu bar. In some cases, you may need to select a "Mixer" or "Effects" window from your menu bar options. On the main project window, you should see a "Volume" indicator directly on each track, which you can use to increase or decrease the volume of each layer. Experiment with all of the available parameters.
Save your completed file by selecting (File > Save) and then convert it to a recognized audio format by selecting "Bounce" or "Export" (this also appears under the "File" menu in most programs). Enter a title, choose a format and click "Save."