For the project I'm currently working on, which is usually hosted in azure and using ACS, I had a need to set up a test Active Directory Federated Services environment for an on-premise install. Active Directory is confusing at first to a non-user, mostly because the term is used for many different somewhat related services.
Looking around the internet, I came across this fantastic article on setting everything up in azure. While I didn't write it, here's an excellent how-to guide to ADFS on Azure:
http://haishibai.blogspot.com/2012/11/complete-walkthrough-setting-up-adfs-20.html