Double-click the desktop icon to launch a digital audio workstation.
Click "File" and select "New" to create a new session.
Import the first song. The exact process varies by program, but you typically click "File" and select "Import Audio." Then browse for the audio file you need.
Import the second song. This will automatically line up beneath the first song. The audio files for both songs will display as wave form graphics. The peaks represent loud points in the song; the flat lines represent silence.
Launch the pitch-correct tool. The name of this tool will vary. For example, in Mixcraft it is called "GSnap" and in Logic it is called "Pitch Correct." These tools are typically located in the "Effects" menu. If you have downloaded a third-party pitch correction tool such as Auto-tune, access it via the "Plugins" menu.
Double-click on the first wave form to open your DAW wave editor.
Play the track. Click "Auto Detect Key" on the pitch-correct interface. The tool analyzes the wave forms and determines the most likely key.
Double-click on the second track. Determine its key. Now you know the key of both tracks, and you can decide which one to alter. Typically it sounds better if you pitch a track up rather than down, so it's preferable to alter the track of the lowest key. This is because you need to alter the playback rate in order to increase pitch and, when you slow a track down, it drags.
Calculate the amount, in semitones, you need to adjust the first track. For example, if the first track is in the key of D and the second is in E, that's a difference of one semitone.
Click on the selected track to highlight it. This assigns subsequent edits to this track only, rather than both.
Click "Effects" and select "Pitch Shift." In the dialog box, enter the number of semitones by which you'd like to increase the key. Click "Save." This alters the audio file so it is in the new key.
Open the "Mixer" tab.
Adjust the "Gain" levels for each audio file until you find a balance. If one track is naturally louder than the other, reduce its gain to compensate.