John, have you tried opening the audio properties for your timeline then dragging and dropping onto it ?
The editing timeline normally shows thumnails like 35mm slides in the timeline window.
I haven't used studio in ages but IIRC you can open the audio when in editing mode by clicking on the middle (long bar shaped) icon in the top RH section of the lower editing timeline area: This then reveals separate split timelines for video, audio, narration, backing audio etc. rather than the 35mm style thumbnails.
I think you then drag and drop your mp3 onto the lower (background music) timeline.
What version of studio are you using? If version 8 you need to upgrade to version 8.12 as previous releases were very buggy. I think Version 9 is pretty mature and bug free.
