2001 Malibu Rear Speakers Problem

Accidentally blew one for sure, maybe both, rear speakers. how hard is it to replace and any info or tips anyone could give would be awesome. I have never done anything to alter my car so please "dumb" it down for me. I can see the bottom of the speakers from the trunk, but i dont know if i would have to replace them from there or from the covered panel above the back seats.

Help Me Please!!