CDA, which stands for "Compact Disc Audio," refers to a file format that your computer uses to recognise CD audio files. CDA files can only played on a CD-ROM, so if you transfer them to a computer's hard disk, you will have to convert them to a different file format. You can do so by "ripping" the music using a program such as Windows Media Player.
Open Windows Media Player. Click the "Rip" tab.
Click the drop-down underneath the tab and select "Format." Select the audio format you'd like each song to be in, such as "MP3."
Insert your CD into the computer's CD ROM drive. The Rip tab will automatically save the CDA files from the CD and place them on your computer's hard disk in the format that you specified. Click the "Library" tab to view and play them.