The Greenstone digital library software is a comprehensive system for building and distributing digital library collections. It provides a new way of organizing information and publishing it on the Internet. This paper describes how digital library collections can be created and customized with the new Greenstone Librarian Interface. Its basic features allow users to add documents and metadata to collections, create new collections whose structure mirrors existing ones, and build collections and put them in place so for users to view. More advanced users can design and customize new collection structures. At the most advanced level, the Librarian Interface gives expert users interactive access to the full power of Greenstone, which could formerly be tapped only by running Perl scripts manually.