as Legend said, magic is not a colour, it's energy found in nature. our intent is what makes it positive or negative 'white' or 'black'.
you should start with the basics of magic. learn how to meditate, charge and ground energy, circle casting, and visualization are key to casting a good spell. once you get the hang of it, cast a couple candle spells for practice. once you feel confident with them, you can try some simple hexes, couple chants, things like that. it all comes down to focus and intent. study magic before casting so you know what you're doing.