How do I patch a cement staircase?

A piece of cement has fallen off the staircase in front of my house (pic below). I just bought the house, so I don't know the history, but it looks like someone attempted to patch it before. How do I go about repairing? I'm guessing that I'll need to chisel the hole out, reinforce, and patch. I'm very handy, but haven't done any masonry work before. Is this something I should be able to handle? Here are my specific questions.... 1. How far, and what shape do I need to chisel out? 2. Do I need to add reinforcement? Rebar? What do I tie it into? 3. What should I use to patch? Regular cement?