There is no way of telling what breed should it be. Many very different breeds come in black. When you start taking lessons, you will learn that there are various styles of riding and even more riding disciplines within these styles. Over time, you will experiment with those styles and disciplines that will appeal to you. Each riding discipline may call for very different set of skills that the horse must acquire to be good at it. And different breeds are prone to have different natural abilities, for example, there are breeds that are bred for speed, for agility, for endurance, for pulling power, etc... There is no perfect breed of black horses that will suit every need of every rider - you will just have to find that out for yourself when you are more experienced and truly ready for a horse (horse ownership is no fairytale!), but, until that, just go out there and learn! You will have to get many, many miles under saddle until you get just a taste from the very surface of the horse world.
I have come a long way, to surrender my shadow to the shadow of my horse.