go to the export menu and choose "audio as <insert format here>" (cant remember what the options are. if it exports as aiff, just open the file in itunes and convert to mp3.
go to the export menu and choose "audio as <insert format here>" (cant remember what the options are. if it exports as aiff, just open the file in itunes and convert to mp3.
you can trim the clip like you normally would before exporting it, or you can use sound studio (included with all non-power machines ie imac, etc.) in addition you can set start and end points in itunes, but i dont know if that would help.