If you do not own All2MP3 go to soft32.com/download_218265.html. Click on "Downlaod" and the download should start.
Unzip the folder. Double click on the file called "All2MP3.mpkg." Run the installer.
Run the program. Drag and drop your files into All2MP3. Choose your quality. Press "All2MP3." The program will convert your file. The converted file will be in the same folder as the original file.