Please keep in mind that DVDAuthor is a command-line program. If you'd like a graphical interface, you'll want to download one of the third-party GUIs instead. Don't forget to check the ChangeLog for information on the latest features.
The official releases of DVDAuthor are sourcecode-only packages. To use it, you'll have to compile it yourself under or get the binaries from a third-party site.
You can usually get the latest binaries as part of the DVDAuthorGUI program.