Over the last couple of month, id Software and Bethesda have done a lot of promotion work. Finally, DOOM is released worldwide in every region and can be played on any platform. If you didn't track the news about the game, you would like to check a few of the following articles: the preview of DOOM's single-player (with Creative Director Hugo Martin and Executive Producer Marty Stratton), the DOOM Snap Map overview (a 1-hour Twitch stream showcasing a map toolkit), and the Multiplayer Beta.
You can buy the game using the official game site.
Lastly, here's your launch trailer.