Create a new music project using your digital audio program. A useful digital audio program would include multi-tracking software, such as Pro Tools, Logic or Cubase. If you do not have access to multi-tracking software, you can download a free program such as Audacity or Ardour.
Check the tempo, or speed, of the two music tracks. In order to line up two tracks perfectly, they must play at precisely the same speed. If you do not own software that reads audio tempos, you can measure the tempo yourself by playing exactly 15 seconds of the track and counting the beats. Then multiply that number by four to determine the number of beats per minute (bpm).
If one track plays faster than the other, you will need to change the speed of one track to bring both tracks into harmony. For example, if one track plays at 135 bpm and the other plays at 145 bpm, you will need to decide whether you want your final product to play at the faster speed or the slower speed.
Edit one of your audio files so that it matches the destination tempo. Set the tempo in your main window to match the current tempo of the file you want to change (as opposed to the destination tempo). For example, if your track is 145 bpm and you want to change it to 135 bpm, choose a tempo of 145 bpm for your audio project. Then load the music file onto a blank audio track (which resembles a horizontal recording space on the mixer) by dragging it with your mouse.
Afterward, change the tempo to your destination tempo of 135 bpm. This will re-render your track to the slower speed. If you cannot find your tempo indicator, look near the bottom of your mixer, or in "Options" or "Settings."
Place the other file on the next audio track directly beneath the file you just added.
Align your audio files so the music on each begins playing at exactly the same moment. If one track has a slight delay, remove it. Trim your audio files using the "Cut" tool or by highlighting unwanted space with your mouse and selecting "Delete" to remove the unwanted delay. Make sure both tracks starts at the exact beginning of the time line.
Match the volume of each track. Because engineers master music tracks in different ways, you will likely find that one file is much louder than the other. Use the volume fader beside each track to bring the volumes into harmony with one another. For instance, if one track is especially loud, drag the corresponding volume fader down until it matches the volume of the other track.
Clean up each track using the EQ mixer provided by your digital audio software. If one track sounds very thin but the other has excess bass, raise the bass frequencies on the thin track to better blend the tracks. To align the tracks, adjust the "Bass," "Treble" and "Mid-Tone" sliders (or the individual frequencies for more advanced editors) for each track until you have a good mix.
Click "Save," which usually appears under "File" in the menu bar, and choose your format. You can typically save your project as an MP3, WAV, FLAC, AAC or other standard audio format.