Begins with taking an honest look at the past. Naturally moving forward towards a new beginning also means you have to leave the past where it belongs. That's impossible to do if you two haven't let go of the conflict that caused you to break up. If your girlfriend dumped you it may seem as though you did nothing wrong, but consider the idea that if she was truly happy, the break up would never have occurred. This is the part of the process where you need to do some self reflection and decide what you did and what you can do to remedy it. Apologizing is always a good place to start followed by changing your behavior.