I too have SonicStage and find it quite intuitive. One thing you have to bear in mind however is that the programme does not use mp3 files, but ATRAC, Sony's own.
The compact disc music that you have 'backed up' will have been converted by SonicStage to the file type I have just mentioned, NOT mp3, which is why the programme is crashing when you try to DIY (I presume).
I do not know, (but would like to!) whether it's possible to convert ATRAC to mp3 or vice versa. Perhaps another reader might have knowledge of a programme that can achieve this? I will be watching this space.