I am new to DND and was wondering if anyone knew about any like.... royal etiquette books and forum? not sure how to put words into paper... so basically for my backstory I need like royal etiquette training? or just etiquette training in general. but everytime I look up like the old etiquette rules and stuff it just brings me to England royals of today and was wondering if anyone had any recommendations.

Talk to your DM. Earth etiquette rules may or may not apply to any of the many possible worlds on which your game will take place. 
And most of the time, this kind of stuff is kind of hand-waved away. Like, your party wants to meet the local baron, and you remind the DM that your character is versed in etiquette, so you’d know who to approach to arrange the meeting, and what you might say. That kind of thing. 
Of course, in a heavy role play group, you might be expected to play out that scene in detail, which brings us back to asking your DM how they will handle it in your game. 

If you're a character, then ask/collaborate with your DM. There's no universal rulebook on etiquette, and if your DM is expecting you to remember stuff in real-time during roleplay, I'd say it's up to them to help make sure you're set.

Greetings Onyx_Lupin,

I assume you have read over items like this:
https://www.thesocialhistorian.com/victorian-etiquette/

Aside of sites like that, as the first two responders stated, this is more of how your DM wants to handle the situations.

Cheers!

What if I do not yet have a DM? where would i go from there?

Then you're kinda putting the cart before the horse, worrying about minutia of roleplay like etiquette. A typical table is more likely to prefer you just say something like "my character uses their knowledge of etiquette to introduce themselves properly" over you spending 5 minutes describing all the steps every time you make a formal introduction.

Quote from Onyx_Lupin >>

What if I do not yet have a DM? where would i go from there?

 Not to be a jerk, but, get a DM. You actually need one of those before you make a character. Many DMs have house rules about character generation, or will run a campaign where some options don’t make sense. So find a game, and then work with the DM to make a character to fit the game. 

The important thing for you is to come up with a character you enjoy playing and you feel comfortable stepping into the shoes of.  If having an intimate understanding of noblesse oblige and other medieval tenants of noble etiquette helps you get into character, then, by all means, do the research and apply some of that to your character—no need to listen to folks telling you to just hand waive away such an important part of your character’s identity.

Regarding not having a DM yet, that is also fine.  Plenty of people come up with characters before playing or finding a group.  Even a mediocre DM is going to work with you if you say “Hey, I have this character idea, how can we work together to make this work in your campaign.”  As long as you are willing to be flexible in some regards, your DM should work with you to insert the core elements of the character—especially if those core elements something generic as “European noble.”

Now, to actually answer your question, your best bet is going to be reading literature from the era you are looking for. Something like Le Morte d'Arthur, for example. These might not be etiquette books, per se, but they showcase contemporary views on how nobles could or should act. 

Research for its own sake is one thing, but it's best not to get too wedded to a specific iteration of how a character should play before you've even got a DM and campaign.

Quote from The_Ace_of_Rogues >>

Research for its own sake is one thing, but it's best not to get too wedded to a specific iteration of how a character should play before you've even got a DM and campaign.

Yes, OP should not be too wedded to the idea and should be willing to work with their DM, as I already said—but telling them they should not bother fleshing out an idea is both unhelpful and ignores a pretty well known reality about how many people play. I can guarantee there are hundreds of thousands of fully conceptualised characters out there with complete backstories, an idea of their starting personality… and no DM or campaign to exist in. Telling a new player not to bother doing something that experienced players do all the time is not exactly helpful.

To OP, I’ll add another piece of actually helpful advice to my “just be flexible and be willing to adjust when you finally have a DM to work with” advice above.  Only come up with how you want the character to start. Backstory is fine. Personality at the start of the campaign, also fine. But do not think much beyond that. D&D is not a game for mapping out your proposed character’s plot—it is a game where you try to make a character you want to play as, then you step into their shoes and see where they want to go. 

Some points, that are hopefully helpfu:

•  Definitely get some actual play experience under your belt asap.
• Building characters is fun - fun is the idea of the game - however, the DM + other players will have a better time if you know how your Rogue/Druid/Whatever works in combat.  That's super-good stuff to be familiar with.  That's not to dump on your concept, but it's almost certainly going to better if you know which world/game you're tailoring it to.
• When I DM (and games I've enjoyed more (not dropped out of)) I use Forgotten Realms, there IS specific Lore/social rules, etiquette and all that sort of infomation available (and it saves me a lot of work).  I very clearly state that's the world and here's the region the game starts in - "come up with a character that has a reason to be in Waterdeep/Icewind Dale or Chult" - and I'll expect the player to have a couple weeks to work something out - maybe with race/class rules on what's allowed - but again, I make that super-clear up front.
• Every now and then, with a whole bunch of setting information having been made clear, there's still the player that wants to shoehorn a character they're "in love with" into a setting where it just won't work or (more to the point) it just won't work for me + I'm entitled to fun too - I want a believable world.  (Fairy Barbarians are an example of something I just don't want - it's anachronistic for me).  It really sucks as a DM to have to tell someone "no" when it's obvious they love the character. 
• Again, make characters, write backstories + writing a good backstory is an art one you will get better at the more you do it, so only good things can come from practicing that skill - just don't get emotionally invested in the character until they're in the heat of combat, or negotiating with some Dwarves or "on the table" with a bunch of people.

As well, "a bunch of people" - an over-written character can easily tread on the toes of other players + their fun.  As a DM - 5x bullet points for your backstory please, 2-3 sentences per backstory - if there's 3+ players that's a solid amount of work for a DM to tackle and keep track of over the first few sessions and hopefully there's some good stuff in there "hooks" that can develop more as a campaign goes on.  1 side of A4 - sure, I'll read it + hopefully enjoy, but I still want 5x bullet points on the Character Sheet as an easy reference for the session/longer term planning.

More than a 1x A4 page...  I probably don't want you in my campaign - that (to me) suggests you think you're the main character and not a "team player", you're making no room for the other people at the table, I would consider that a Red Flag.  By all means write it, have stories, anecdotes - nothing beats a PC RPing a stupid story about a tavern brawl where they know the location and people that were there, but if you make it "Meeting Lord Neverwinter", well, that's a powerful dude, how did you know him?  ...and suddenly your character can start to become a bit overbearing (see Main Character Syndrome).

I had a player present "Grub, the boring farm boy" as a Fighter, his family killed by beasts.  Grub could tell you his family history going back generations + the most interesting thing about him was an Uncle that was a cartwright and not a farmer "as was the family tradition".  Grub was excellent, he'd consistently fail Charisma checks because any opportunity, he'd tell his boring family history - it worked really well for the party who decided to broaden the kids' horizons for him - but that was the point, it worked really well with the party, the players were great at turn taking and it was just "adventuring party hangout" + sometimes combat.  Find yourself a game that you can regularly commit to and see what ideas the DM has, because you could end up finding a great game - just not in a world you'd considered before and no you need to think of something fun for a Space/Ancient Greek-type/Feywild/Dragonlance setting - they're all different, but a good game is a good game and the sooner you're on the experience curve the better.