1997 Dodge Intrepid oxygen sensor

I'm replacing the oxygen sensors in my intrepid, I needed to know how I would do that, I already priced the parts, I was wondering what tools I would need and where on my car are the sensors located. There is also another sensor I need to replace but i'm not sure what its called it has something to do with the oxygen gas mixture that keeps the engine firing correctly, is there anything I need to know before I replaces theres parts