How do I convert to a .CDA file to write a CD?

[Spoons]

You are 'barking up the wrong tree' so to speak. What you should do is convert your audio files to Wave files 44.1Khz 16 bit Stereo, all CD writing programs will be able to take these wave files and create an audio CD. Just make sure you create an Audio CDin your CD writing program as apposed to a Data CD.