Create a public course
Public courses are available for the world to see. Your course content will be searchable by anyone browsing iTunesU. Generally, Public Courses are the easiest for students to access. Public courses need to comply strictly with Copyright law, and do not fall under fair use provisons for classroom use.
Create a private course
Private courses offer the security of knowing that your materials will only be viewed by your students, and can only be accessed by students through a widget in the course D2L page. Private courses generally cause more problems with student access. Private courses allow instructors to place materials that may be in copywrite gray area, IE items that may fall under fair use provisions for classroom use.