D&D is a role-playing-game which means that you, as a player, control an character which is put up against challenges and you have to make them react to whatever the DM (Dungeon Master or Game Master) throws at them.
⚔Erdan Darante⚔
Below is the official D&D beginner rule book and a short beginner campaign.
If you know the basic rule of D&D below are the official D&D Corebooks with some other supplements.