Programming in D is an extensive tutorial by Ali Çehreli and a great starting point for absolute beginners. It doesn't assume that you know any other programming languages, and it also teaches you about some fundamental concepts of programming.
Other than that, the best places to learn are:
- The D Wiki, which tends to contain the best information and links.
- The Forums contain very active discussions, in particular D.learn for new users.
- The Books listed on the Wiki.
For a little more depth:
- Download a compiler.
- Choose an IDE or set up your favorite Editor.
- Read the official Language and Standard Library references.
- Browse the Dub Repository, hosting an ever growing list of 3rd-party D programs and libraries.
Welcome to D.