Fifth Edition, definitely. The various editions are largely incompatible. Here’s the Amazon link, just in case.
The DMG and Monster Manual are 58% off.
Welcome to the game! To start you'll need a few things, and can expand from there.
Here is the basic rules, as well as basic Dungeon Master (DM) rules. They are available in a web based or printable format.
Here is player sheets and some premade characters if you don't feel like going through the process of creating a character to begin with.
You'll also need some dice. Chessex makes some cheap dice to start with.
Here is a nice DM screen/cheat sheet that has information you'll probably need at a glance while running the game.
Think about getting the Starter Set . It comes with a pre-written adventure module, basic rules, premade characters and a single set of dice for a reasonable price.
After that watch Matt Colville on YouTube. He has a very nice series called "Running the Game" that is filled with information and tips, and starts off with a complete beginner in mind.
If you want to start getting serious I would recommend each player getting a Players Handbook . This has information for creating a character, rules for playing the game and other useful information.
As a DM you'll need the Dungeon Masters Guide and the Monster Manual . This has information and rules on running the game, and stat blocks for monsters. You can get all three of these mentioned books in PDF format if you wish, but I find physical copies to be easier to quickly reference.
Here is a website that has infromation I've previously mentioned in a nice web format. It is not a replacement for the books I have mentioned, as some of that information isn't on here.
After all of this you may want to get Volo's Guide to Monsters and Xanathars Guide to Everything . This has even more monsters, player races and variant rules you can add into your game. These are not mandatory but I find them to be a nice addition to the game.
You may decide to start using battle mats and miniatures, these add a lot to the game by making combat more visual and tactical. To start you could do something as simple as printing off squares on paper . This last part can add a lot of expense to the game and isn't mandatory, but most people prefer to use them.
That's a good introduction. There's resources on Reddit to learn the game, including /r/DnD, /r/DMAcademy and /r/DNDBehindTheScreen as well as YouTubers such as Matt Colville, Matt Mercer/Critical Role, Nerdarchy and Web DM.
This is a prewritten message that may not completely apply to you, but it summarizes a lot of the information that a beginner player or DM could use.
There's one online for you! Amazon is a good resource for stuff like that.
D&D 5th Edition Players Handbook
D&D 5th Edition Dungeon Master's Guide
D&D 5th Edition Monster Manual
Pound-O-Dice (I mean, you probably don't really need a pound of dice, but you get the idea what kind of dice you need...unless you get him a pound of dice, and then that would just be awesome!)
I recommend giving this a read .
I've always found it difficult kicking off a new group because of how vastly different the PC's usually are. Honestly, just get creative with it.
>They're in an Inn, but all of the sudden there are cries coming from outside! The town is being raided by bandits! People are fleeing upstairs trying to board up their rooms! The main door is lit ablaze so there is no way to get out! (Maybe the innkeep has a secret door?)
This could be a jumping point. Now the PCs have to work together to get out. This gives them an enemy to focus on as well as setting up your world. From there you can branch off and setup events going on in different directions of the world in correlation to their current location (North, South, East, West) so that if they decide to leave the town high and dry there will be some content for you to work with.
Edit: This goes from typical cliche starting point to an interesting twist