Are you asking for the rules to D&D the tabletop game? Because those I can legally link you to, and in several versions to boot:
>OSRIC gives you access to the old school Basic D&D rules used in the seventies and the eighties. Simple to learn, but you'll have a hard time meeting fellow players. http://www.knights-n-knaves.com/osric/>Pathfinder is the most popular version of D&D played today. It is very rules-heavy and complicated, but also gives you a lot of options and adventures.http://paizo.com/pathfinderRPG/prd/> Dungeons & Dragons 5th edition is the official game updated for a more modern audience. It is not as much of a chore to understand as Pathfinder, and has a nice big player base.http://dnd.wizards.com/articles/features/systems-reference-document-srdAlternatively, you might have meant that you want to play the D&D MMO? It's called Neverwinter, and it's Free2Play in Steam.
