Find a website that converts music for free. There are several listed in the resource section that work well.
Decide what elements you would like to change. Most programs will let you modify the bitrate, frequency and number of channels. In general, you will want to choose at least a 16 bit rate, have a frequency of no less than 24000 hertz and use stereo channels.
Upload your file to the online program. You will see a progress bar that indicates how much time you have left on your audio file. When the conversion is complete, the file will automatically download. Most online audio converters have ads that help to support their service. Read the instructions and don't click any download links that will redirect you to their software.