The File menu contains the following items:

New Playlist
Opens the playlist window and clears the contents.

New Linked Playlist...
Creates a playlist, linked and synced to an existing folder

New Control Window
Creates a new Audion control window

New MP3 Editor
Creates a new MP3 editor window for editing MP3 contents

Open…
Opens a file for playback.

Open Stream…
Allows you to enter the URL of a streaming MP3 server, or click to open the Stream Guide window. A streaming URL is in the form 'http://server.com:port'.

Open MP3 In Editor…
Opens an MP3 for editing in the MP3 editor window.

Open Playlist Quickly
Provides quick access to playlists in the 'playlists' folder. When you add playlists to this folder (which should be in the same folder as Audion itself), they'll show up in this menu.

Close
Closes the active window, whatever it may be.

Hide
Hides the active playlist window.

Save
Saves the current item (playlist or edited MP3)

Save As…
Saves the current item after asking you to name it first.

Quit
Quit Audion? What's wrong with you?