When you select a file, a new project is created and your selected file is populated as the first track. You can now record new tracks on top of your imported file! Keep in mind that Spire allows you to import only one file per project, and you cannot import a file to an existing project.
Supported file types:
.wav (stereo only)
.spire files (Spire projects)
*Files that are greater than 60 minutes long cannot be imported.