You can find the basic rules here . The Systems Reference Document (SRD) as one document is here , though it is available in searchable chunks within Roll20. Please not that while either document contains enough information to run a basic game, neither one is anywhere near complete. They are intended to allow people to "dip their toes in" or to produce basic content to self-publish (check the rules and disclaimers Wizards provides before attempting the latter). The Basic Rules tell you how to play, the SRD is a collection of character generation rules, Spells, Equipment, Monsters and other resources. As for learning to play, the absolute best way is to find an existing group or DM willing to teach (there are many on the Group Listing which advertise that they accept newbie players). Failing that, there are any number Youtube How To Play videos. I would suggest the folks at Nerdarchy for the most comprehensive collection of D&D 5e videos. If you are looking for content, Roll20 provides a free adventure called The Master's Vault (you can find it on the Start New Game page), that will walk you through an adventure for beginning players (Though it still requires a Dungeon Master).
