Navigate to an Online Audio Converter using your Internet browser. When the site loads, you will see a window with a browse button beside it. Click the "Browse" button, launching a window showing the contents of your computer. Navigate to the folder which stores the audio files you wish to record to CD.
Select one of the files and click "Open." Click the "Upload" button of the converter website. The website will start the transfer of your file to it's server, showing it's progress in a bar that appears on the screen. Once the file has completely uploaded, you will have the option of choosing which file type you wish to convert the audio file to. If you are converting a ".wav" file, an ".mp3" will drastically drop the size of your file without losing much noticeable quality. If you are already working with an ".mp3" file, converting the file to ".wma" will lower the file size slightly.
Choose a quality setting from the available list. The options are organized by kilobits per seconds. A commercial CD will always contain audio at least 256 Kb/s. Choosing 192 Kb/s will not cause you to lose much in the way of sound quality, while choosing 128 Kb/s will cause a noticeable quality loss. 92 Kb/s will allow much more space on a CD but will convert to a very low quality audio file.
Press the "Convert" button when you have made all your conversion options. The website will begin the conversion, bringing you to a page where you can download your newly converted file. Choose a location on your computer where you wish to download the file to.
Repeat the conversion process with all the audio files that you wish to record to CD. With the newly shrunken files, you will now be able to store more audio files on a CD, increasing the capacity of the disc.