You have already downloaded RAR files. Thus, next step is to extract original files from RAR files. You can google for a WinRAR for the purpose. Your other questions - 用電爐下載了一套鈴木小提琴的伴奏CD,可是怎麽聽不了呢?大家都用什麽方法下載? will not be any questions once you can extract music files from RAR.
If you already have WinRAR, it will allow you to continue using by just clicking the CLOSE button in the licenses screen.