Winning a Ranked match wont come easy. It takes knowledge of your character and knowledge against your opponent's character. The more you play the easier wins will come because you will learn the tendencies of online players. People are creatures of habit and you will notice that people repeat the same things over and over again online.
You only need to win once to earn this achievement.
Kim Wu is fast. Like stupid fast. Her heavy Dragon Dance kick is a great combo opener. The real secret is to always end combos with the Dragon Kick. It does so much damage.