Confused about the SC2 rating system

So I finally got SC2 about a week and a half ago, and I jumped right into the ladder 1v1s without any practice. I did really poorly at first. I haven't played Brood War in ages, and I only had a tiny amount of experience with the Beta, so it took me a bit to learn new tech trees and general strategies. I got placed in Bronze and my first 15-20 matches were like 50:50 win/loss so I was stuck around rank 50. I'm pretty competent at micro and once I figured out what I was doing my macro ability jumped up. I'm now rank 4 Bronze, and I've won 8 out of my 10 last matches and most of my opponents have been upper ranked Silvers. Most of my opponents are easy as hell to beat. How many games do I need to play before I get moved up?