There are many ways to create an .mp3 file. Some methods include creating an mp3 directly from your editing system including Audacity, Garageband and others.
My preferred method is to use the free iTunes software. This gives you a better sounding file due to the technology (Fraunhoffer (best for voice)) that iTunes is using to compress your audio into the .mp3 format.
The video below shows you how to setup your iTunes software for compressing an uncompressed file (.wav or .aiff) into the .mp3 format.
The settings shown are my preferred settings for audio only (mostly voice) for podcasting. You can change the bit rate to your desired setting for the best compromise between size and quality.
After properly setting up the iTunes software to create mp3’s, I’ll show you how to add in metadata to your file. ID3 tags are the information that helps identify your podcast episode within someone’s portable media player such as an iPod, iPad, or Android device.
This information will display each episode’s title, description and album cover art as well as any other information you choose to include.