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 - 用电炉下载了一套铃木小提琴的伴奏CD,可是怎么听不了呢?大家都用什么方法下载? 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.