Microsoft released a Test Lab Guide which explains in detail how to synchronize an organization Active Directory with Windows Azure Active Directory.
Organizations moving to a hybrid cloud want to be able to provide identity management for services running on Windows Azure whil not depending on their on-premise Active Directory.
By using Windows Active Directory Synchronization Tool (DirSync) on-premise AD can be synchronized to Windows Azure Active Directory.
This 48-pages documents explains step by step how to sign up for a free trial of Azure, how to enable WAAD and how to setup and configure DirSync.
Since November 2013 DirSync can be installed on a server with Active Directory installed. So only a single DC is needed to be able to use this Lab Guide.
More information and download of the guide here.