Open your preferred digital audio workstation, or DAW, for example Pro Tools, Logic or Mixcraft.
Open the song to which you are adding a fade. Typically, recent sessions are located in the file menu. For example, in Logic, click "File" and select "Open Recent." Then select the song to be faded from the drop-down menu.
Export the track as a WAV file. This option is typically located in the "File" menu. Exporting as WAV combines the collective multi-tracks into a single, lossless file. When prompted, save the file as "Song Title Master Mix." To apply a fade to a song, you must save the mix as a single file, otherwise the fade will only apply to the selected instruments. This negates the need to apply individual fades to each channel.
Close the current session and open a blank one.
Open a new audio channel, either from the "File" menu or by clicking the relevant shortcut icon, typically a "+" sign on the channel strip. This opens a single audio channel. Name the channel "Song Title Fade File."
Import the WAV file that you exported in Step 3. The import command is typically in the "File" menu.
Open the Automation tool, either from the "Tools" menu or by double-clicking the audio channel. This opens the file as a sound wave graphic, comprised of various peaks and flat lines. The peaks represent volume, the flat lines represent silence. The sound wave graphic is superimposed on a grid. The vertical axis represents volume and the horizontal axis represents time. Just above the horizontal axis is a base line, this represents silence.
Click on the sound wave, at the point you want the fade to begin. If you want to fade in from silence, click below the base line. If you want to fade out from full volume, click on the top of the grid. By clicking on the grid, you establish a starting volume and a starting place for the fade, enabling you to effectively draw the fade onto the sound wave.
Click on the sound wave a second time. This establishes an automation line. The gradient, direction and length of the line determine the nature and intensity of the fade. For example, a steep upward automation line will create an abrupt fade-in. A gradual, downward automation line will create a slow fade-out.