328 trunk layout

Help, I have several loose pieces in my trunk that the previous owner had taken out to replace the antenna. I am not sure if the antenna is the right one but it seems to fit ok. My question is about the 2 fiberglass backed foam panels and other items. I suppose the foam panels fit flat on the top of the floor on each end with the ribbed formed panels on top. I have a carpeted piece roughly 10" x 12" with notches cut out and velcro that I can't seem to find how to put in. Does it cover the antenna some way? (I need to go look in some trunks, right?) Anyway, thanks for any help.