SonicStage/Atrac3 files--How do I import these files and convert them??

This is my problem.

I used to have SonicStage, I no longer do, but I found some of my old CDs that I made using that program, but the atrac3 files(I believe that's what they're called) aren't compatible with Mac, so now what do I do? I've never converted anything in my life, are there any apps I could download that will rip the unreadable files from my old CDs and convert them into usable mp3 (or whatever) files?

This is all very foreign to me and any advice would be greatly appreciated.