Apple has some great documentation that helps users to get up and running on iTunes U very quickly.
Creating Content for iPod + iTunes discusses the various file formats iTunes supports as-well-as which file format is the most appropriate for your needs. The document does highlight Apple's content creation tools (QuickTime Pro, GarageBand, iMovie, and SoundTrack). If you're using a Windows PC, we suggest that you explore tools like Audacity for recording your podcast, and Propaganda as an alternative to Apple's GarageBand.
iTunes U User's Guide explains how iTunes U works and how to add-to and edit the content that you post to iTunes U.
Apple's Copyright Overview gives a brief description of some issues involved in copyright law as it applies to the Internet. Many of these issues have been addressed by Maryland's legal counsel, but this document is still worth reading if you would like to gain a better understanding of how copyright law is applied to content created for distribution through iTunes U.