iTunes or not
iTunes and iPods are frequently connected to the topic of podcasting. While the iTunes store is a useful place to find podcasts, and can help increase the visibility of your podcast, you do not need to use iTunes as part of your podcasting regimen. In general, if the purpose of your podcast is to reach an audience outside of your school community, and/or you are creating a series of podcasts over time, then iTunes could be a good way to extend the reach of your podcast.
In situations where the podcasts are informal in nature, or where podcasts are more of a regular means of communication, iTunes is an additional step that adds little value to the teaching and learning involved in creating podcasts.
If you want to add your podcast to the iTunes store, Apple has laid out the process on their website. Navigate to http://www.apple.com/itunes/podcasts/creatorfaq.html, and follow the link provided in the How do I submit my podcast? section.