How do I get the self service app?

MY teacher said that the self service app needs to be found first to install iTunes U. Then I go under my courses and click on enroll a course. I attend Paul v1 high school

Kristapink11 wrote:

I need the self service app to download content from my district

Can you expain in more detail what you are talking about? What content exactly? What district? Do you have a reference to the "self service" app? I have never heard of that.