Unbolt the old one. Unplug the connector. Plug the new one in and bolt it in place. To prevent setting a diagnostic fault code, don't turn on the ignition switch while the bag is disconnected, however, the codes are already set if the bag deployed. Since you included so many details, I have to guess the bag was set off. If so, most manufacturers state to also replace the clock spring under the steering wheel because the electrical connector is likely melted from the burning rocket fuel. That typically requires a steering wheel puller, available at Harbor Freight Tools and Sears. Replacing those is fairly easy but there are critically important steps you must follow to prevent damaging the new one. Those steps are spelled out in the service manual and will include drawings. Basically you must start with the wheels perfectly straight ahead, and they must remain that way until the new clock spring is in place.
They also specify replacing the Air Bag Computer and front crash sensors if they're still used. There's a 99 percent chance those parts are okay but they are concerned that the sensor contacts may have an arced spot where the contacts made a spark, and they're worried, for liability reasons, that in another identical crash one of those arced spots could prevent that sensor from triggering a second time. If you don't replace the sensors, and the computer with a sensor in it, the system will pass all the self tests each time you turn on the ignition switch, but the bag may not deploy in another crash.