Add Track to Playlist
You have several options for adding tracks to your Playlist.
From the Music Library:
Double-click on a track to add it to the Playlist.
Drag and drop a track into the Playlist.
Use the Find button to locate a song in the Music Library and click the Add button.
From the Desktop and Sub Folders:
Double click on an MP3 file to launch MusicMatch and load that track into the Playlist.
Drag and drop an MP3 file into the already open Playlist.