this is a quick informal guide to d&d for anyone.
d&d is a roleplaying game. so let me explain roleplaying games real quick.
a few people sit down for a few hours, taking the roles of imaginary characters in an imaginary world.
it's like playing pretend as a kid, but there is a more formalized system for arbitrating disputes and setting general limits on the laws of physics.
d&d is set in this pulp-fantasy mashup world that tends to make the game weird, funny, and melodramatic.
in d&d, the characters are trying to get things done or find treasure or probably both. usually this means danger, and often lots of fighting monsters or bad guys. but characters don't always have to fight and there are often cleverer solutions and cleverer ways to fight. and a lot of the game is actually investigations and talking to non-player characters and procuring weird supplies.
the players are helped by one helpful person called the dungeon-master or DM, who sets up the world and keeps the rules and acts as a referee and moderator. the mastery of the DM over the game itself is a key component of D&D.
the game is very open-ended. the characters can do anything that occurs to you. they are not limited to certain well-defined moves. there are rules, but it usually comes down to the DM's judgement.
for that reason, being good at d&d is really about creative problem solving and weird ideas and working together and having fun. it doesn't matter if you know all the rules or anything like that.
d&d is supposed to be fun. this can only happen if people are nice to each other and cooperate to make the game fun for everyone. so everyone should avoid making people uncomfortable (e.g. with unreasonably gross, or bigoted jokes) and respond to reasonable requests for accommodation. intentional trolling and bigotry are right out.
a major though unpleasant function of the DM is to kick you out of the game if you're being a jerk.
to play the game, you need a character to play as. so before the game, the players choose or create characters they want to play.
there are ready-made or "pregen" character sheets you can use. this is easiest. if you do this, you can skip this section about making a character and just use the ready-made one.
the "official" pregens are here, under the heading "Pregenerated Characters": http://dnd.wizards.com/articles/features/character_sheets but official doesn't matter; there are tons more here: http://www.digitaldungeonmaster.com/dd-5e-character-sheets.html
otherwise:
the worksheet for creating a character is called a character sheet. you can download sheets here: http://media.wizards.com/2014/downloads/dnd/5E_CHARACTERSHEETSV3.ZIP you probably want to use "DnD_5E_CharacterSheet - Form Fillable.pdf" if you are not just printing it out, then it doesn't matter. you can use http://orcpub.com to automatically compute most things you would want.
choose one of the "races" (species) and "classes" (adventure jobs). don't agonize too much about it, just choose stuff that has a flavor you like! you can always try something else next time.
you can pretty much just choose your character's general physical description, like your height and weight and various colors. go nuts, as long as it doesn't give any special advantage and basically makes sense for your character's species.
choose whatever name you want for your character or ask others to help make one up. random fantasy names are better than stuff like "stupidface mcgee." needless to say, things calculated to offend the other players are not ok.
if you hear about "alignment," don't worry too much about it. it was supposed to help people play characters with consistent motivations, but it never made much sense and you'll probably just change it anyway.
to do the specific stats stuff, you can look at the basic rules PDFs or you can use http://orcpub.com to compute everything for you.
write this stuff down and save it somewhere.
you don't have to know everything about the game's rules. mostly, the DM and other players can help you with that stuff.
but here's the basic deal in D&D:
the DM describes a situation.
then the players decide what their characters should do. you do not have to act the character or do a voice; you can just say what the character does. it's better not to tell other players what their characters should do, unless they are looking for advice.
the DM figures out the outcome using the rules or (if necessary) by just making a decision. when it comes to the rules of the game, the DM's word is law.
here's a PDF containing basic rules of the game: http://media.wizards.com/2016/downloads/DND/PlayerBasicRulesV03.pdf
here's a list of spells if you need one: https://media.wizards.com/2015/downloads/dnd/DnD_SpellLists_1.0.pdf
when the outcome of a character's action is dicey, the DM may call for dice to be rolled. this is a huge part of the d&d ritual.
the DM decides how difficult the task is and picks a number. the higher the number, the tougher the odds. then the DM asks for a dice roll.
you roll a 20-sided die. higher results are better.
if you happen to roll a 20, that's a "natural 20," it means you automatically succeed and often something neat happens.
if you happen to roll a 1, it means you automatically failed. it doesn't actually mean your failure is more harmful or severe.
otherwise, if you didn't roll a 20 or a 1, you usually add some number to the result, representing your skills or abilities. which ones depend on the DM and the rules. if the total is equal to or higher than the difficulty number, the action succeeds. otherwise, it fails to succeed.
if the situation is unfavorable, the DM may have you "roll at disadvantage": roll two 20-sided die instead of just one, and take the lower number.
if the situation is favorable, the DM may have you "roll at advantage": roll two 20-sided die instead of just one, and take the higher number.
if the situation is both favorable and unfavorable, they just cancel out and you roll one 20-sided die. summing up lots of numbers is for the birds.