Share 'New to biking and need advice'

Hi I have finally sold my car, am moving downtown and have decided to purchase a bike (this week). This will be my first time on a bike since I was a child, and I'm not too young. Can someone please give me the rules of biking in the city? Must I stop at a red light with the traffic, or can I just slow down and then cross the street if no cars are coming? Since it's not really a car I'm driving i…