How to replace the coil #5 and where is the.

It sounds like you have a V6. I am not sure which bank cylinder # 5 is on but it should be easy to find. Remove any plastic covering and then you will see black wires and tubes that go down into the engine. Assuming the #5 coil is dead, in order to find it just disconnect each coil until when you do, the car doesn't run any different. Then you know you have found the bad coil. Good luck.