Download and install the MP3Resizer software (See Resources).
Launch the MP3Resizer software.
Click the "Add Files" button on the tool bar.
Locate the MP3 file you want to resize. Click "OK."
Set the options for your down-sample. The process will reduce the sound quality and make the resulting audio file smaller than the original.
Click the "Preview file" button on the toolbar to hear the difference between your original file and your down-sampled file.
Click the "Resize!" button on the right sidebar. The smaller file will be created and can be burned to a CD or transferred to an MP3 player.