How to remove the amplifier in a 1997 Ford Mustang?
 

I have a 1997 Ford Mustang Convertible. It has a 460 MACH audio system and the left door speakers are not working. I took it to an audio repair shop today and they determined that it was the amp that was not powering the left speakers. It would cost me $75 just for them to take it out so I said i would do it, but the problem is I am 16 and I don't know too much about car electronics. I replace the speakers in the right door so I have a little knowledge but not enough to know how to take out the amp. Can you tell me what tools I will need and how to access it to take it out.