All in the tittle. but just to let you know i already know how to play a godly 
. well not amazing because im in bronze but good for my skill level. ive been playing since around late s3 so just i have a good knowledge of all champs. just let me know
Well as you claim to be great with Graves, I would recomend him. In lower tiers its best to stick to what your good with. Not what the pros are good with.
But some general tips.
1: 
These are the single most useful item in the game, use at choke points or areas you know the enemy will be at within a minute. intercept and destroy, then take objectives.
2: Objectives > kills. If the enemy support gets away after a team fight and 4 enemies are down, don't chase them. Take a tower / dragon / something. Kills may be nice to gloat about, but objectives win games.
3: Good attitude. Flaming team mates after simple mistakes will hurt you. It'll throw you into a raging fit that will impare your own judgement and you'll walk into traps or die stupidly. Also your team will hate you if you rage.
since you are good with graves, I would have to say graves. it doesn't matter what you play really, any champ can carry bronze if played good enough so use your best.
If you're good at it, I think jungle and support are the easiest two roles to carry from, just because those are the roles that most affect the whole team and have opportunity to get -other- champions besides yourself rolling. Also because most Bronze players totally ignore the vision game, and those are the two roles most engaged with vision. Remember, wards save lives! For both roles, you do have the added challenge of needing to have at least one damage-dealing champ and one tanky champ (so you can balance team comps).
That said, I'm maining Tristana ADC. I'm good at her, I enjoy playing her, and I don't generally have to worry about getting my role - ADC is not very popular in Bronze. It's really hard to play with a bad support and most Bronze supports are terrible. Support mains are a different case, but most supports are someone forced into playing an unfamiliar role that they are unhappy with as last pick. That makes it hard to ADC. (Be sure to thank your support for being there whenever you get a good one... and remember, in Bronze 'good' is simply actually buying a gold item and sightstone, and not feeding multiple kills to the enemy adc with bad positioning. Great supports will actually keep you safely surrounded with wards and get clutch plays to get you fed, and save your hide with pings when you tunnel vision and they see that jungler coming in on the wards they placed. Don't expect great supports, most of them will climb out of Bronze in no time.) My second role is Morgana/Braum in support (preferably Morgana unless we desperately need the tank). If I can't get my main role I can at least ensure we have a somewhat competent support by taking it myself instead of letting last pick get forced into it.
Anyway, while I haven't climbed out of Bronze yet, I -do- have consistently more wins than losses (excluding my terrible provisional matches) so I feel it's just a matter of putting the time in. I'm happy with my formula so far. :)
I think you can carry yourself out of Bronze in -any- role, but you'll do it faster if you stick to your main champ, main role as much as possible. Of course you should have a couple of champs you can play in any role so you can survive picks and bans when someone takes your favorite role and someone else bans your favorite champ in the role you're left in. As an ADC main support second, I don't have much trouble with this - nobody bans ADCs (except rarely Jinx or Kalista) and nobody bans supports other than Blitzcrank (which they do fairly often.) I do recommend having reasonably strong but not OP or flavor-of-the-month champions for your non-main roles. (That's most champions, league is a lot more balanced than you'd think from the forum QQ's). You don't want to be putting a lot of time into practicing multiple champs outside of your main roles which you'll have to do if you use anything frequently banned in your non-main roles. Even though Graves is currently quite strong, he doesn't draw a lot of bans, and even if he did, if you like the ADC role you could easily pick up one or two other ADCs.
Good luck on the fields of justice!
Generally, it's a good idea to be well-acquainted with all roles. There is nothing worse than having someone who doesn't know what they're doing playing a role on some 450 champ that they only got so they could play draft mode a while ago, especially when they're your support. Being very good at Graves, an ADC, I'm sure you're familiar with that guy. Lol.
Any role can carry, but some roles are better for it than others under certain contexts. I'll do my best to put them in an order of easiest to carry with to hardest to carry with.
ADC - Very easy to carry with. ADC's have pretty much the highest lategame damage. They're easily blown up, but you have at least one person (the tank) whose job is pretty much to protect you in a teamfight. I mean, it's in the name for a very good reason.
Mid - Being a burst mage, typically, you should have plenty of damage to dish out. The only difference is that you very often times are much more ability reliant. Factor in that you can get over 1000 AP if you really want to build for it.... that's a lot of damage.
Junger - This one is harder to categorize. You can play tank junglers, or you can play assassin junglers. Assassin junglers are really good for carrying because of their high damage, and the unique ability to farm almost completely uninterrupted. You have to deal with no minion wave to stand behind, but you have to balance the ability to free-farm somehow, right? It's a little harder to know how to carry as a tank jungler, because your job in the late game is to take hits like a champ and hopefully dish out damage or cc. As a tank jungler, you job is more to facilitate kills in lane, which makes it easier for your team to take objectives.
Top - This one is almost always a tank, and, no matter how many times you kill an enemy, that won't always carry over to taking objectives better. If your adc deals no damage, then it's going to take a long time to take your opponent's towers, even if you're the most fed tank ever. The best way to carry as a top is to do the same as a tank jungler, but more in the spirit of using teleport to make other lanes a living hell for your opponents. If you're an assassin top like Fiora, do a good job, and you'll have the other team raging and arguing with each other so bad you'll keep getting kills and taking towers for pretty much free. This one is lower than jungle, because it's less common to have an assassin top than an assassin jungler.
Support - let's face it, supports are almost explicitly told not to ks, unless they're going to get away and you can safely pick up the kill. Unfortunately, being good can't always land you a win. Even if you are a master of playing Lulu support, that can't fix a horrible carry that dies all the time. Supports can have damage in the late game, but if you're so far behind out of the laning phase, you aren't scaling anything. You're too busy trying to save your towers. Know how to do this well so that the ADC's that know what's going on can win with you, but don't take support actively to try to climb in soloqueue. I know for a fact, some ADC's are beyond saving short of sending them to practice.
overall if you want some helpful picks for good champions in each role, just ask about a role or two and I can give you a few options, keeping in mind that you seem to be fond of playing Graves.
I went from bronze four to plat five using Talon And Zed, if not mid AD Vayne Or Top Riven. Key is too win lane [If have trouble on that do normal's]. The key is to roam then get objectives like drag while roaming. If you won lane obviously the other mid cant catch up to you unless she some how gets a penta. Group up early after your roam [Go mid]. 
Couple seasons ago I carried myself out of bronze with a taric, and last season carried myself out of silver with janna. As long as you're great at the champion you picked and don't have a 4v5 match, there will always be a good enough chance for you to win
Any role that can secure objectives, protect teammates, excel in combat, and aid in teamfights. Split-pushing optional. Good attitude is an utmost requirement.
So basically whatever you're good at. Don't afk farm, take objectives over thirst, blah blah blah. Buy wards too.
AP BlitzCrank Mid. You wreck towers. Entire Teams and you have a pick.
