Here you go
These two links should help you.
One is for installing a radio in the 6th gen Accord (this should help you with the wiring for the radio & speakers)
The other is installing front speakers on the 6th gen Accord. That should help you on taking off the panels and removing the speakers.
Just put the left speaker in the right door and vice versa. Before you put the door panels back on, turn on the radio and see if the same problem in the same location is still there. If it is, there's a wiring priblem. If it's not but in the opposite door now, there's a speaker problem

Installing a radio on a 6th gen Accord
Installing front speakers on a 6th gen Accord