Download an audio recording program. If you use Mac OS X, you may already have a copy of GarageBand in your "Applications" folder. Otherwise, you can download a free program online, such as Ardour, Audacity, QTractor or Rosegarden.
Open your recording software. If you just want to record your song onto one track (meaning that you will record every instrument or voice at the same time using one input source), you can proceed to the next step. If you want to record multiple instruments and microphones by yourself, however, you will need to create multiple tracks, so that you can record each track individually. To create multiple tracks, locate the "New Track" or "New Audio Track" selection on your menu bar. Create one track for each part (for example, vocals, guitars and drums).
Connect your instruments or microphones directly to your computer for distortion-free recording. If you own an electric guitar with a standard guitar cable, for example, you can connect a 3.5mm adapter to the end of your guitar cable and insert it into the "Line-In" port on your PC. For XLR microphones, you might need an XLR-to-USB cable. If you want to record without connecting directly to your computer, understand that your recording will contain some white noise.
Begin recording. Your software's "Record" button should appear as a large red dot or circle, sometimes along the bottom of your software window, other times at the top. If recording onto multiple tracks, select your first track with your mouse (it will look like a horizontal bar, stretching across your software window) before clicking "Record," and then record your first instrument or vocal selection. When you finish recording, press the space bar on your keyboard or click the "Stop" button. Repeat this step for additional tracks if necessary, until you have successfully recorded each part of your song.
Add audio samples to your song to fill in missing pieces. Sites like Looperman, Loopasonic and Free Loops offer royalty-free audio samples, including bass lines, drum beats, sound effects and more, which you can add to your song for enrichment. For example, if you record guitar and bass, but do not have a drum set, you can download a drum loop (or several drum loops) and add it to your mix. Just place loops on their own tracks to separate them from your recorded material.
Locate your "Effects" menu and add audio effects to each track. You might find your effects under your menu bar, in a separate editor window or on your mixer screen (which resembles a series of gray columns, known as channel strips). Sometimes the option reads "Inserts," instead of "Effects." Using this menu, you can add effects like echo, distortion, reverb and more. Try multiple effects to get the best sound from each track.
Save your song. When saving an audio file, the "Save" process and the "Export" process are two different but equally important steps. When you save your file (File > Save), you save your progress as contained within the audio project, with all of your tracks and recorded regions. When you export your file, you save it as a self-contained audio file, like an MP3. To export, click "File" on the menu bar and select "Bounce," "Export" or "Save As Audio File." Then just enter a title and choose your audio format.