You're level 14, man.
Look, I'm going to be real here.
Try to practice general mechanics of the game before maining a role. You need to know the basics and interactions of the overall game before you get specialized. Also, if you don't limit yourself to one role now, you'll have a wider view of the game and more overall knowledge of every role and how to apply that knowledge to playing adc (you won't expect your support to be your slave, you'll know how to position instead of relying on peel, you'll know how to play behind instead of expecting your jungler to spoonfeed ganks and save you, etc).
You can always main adc whenever you want, just don't limit yourself yet. You don't need training, you need practice of the overall game first.