I'm not exactly sure about the 96 as I have a 00. If it is similar, here is what you do.
First, pry out the sail panel (The panel right next to the side view mirror)
Pull the trim from around the door handle.
Behind the power window switches (The whole ass'y just pulls out) there are a few screws which must be removed.
In the front of the door panel (The part you can't see when the door is closed...faces forward when door closed) there is one of those pop fasteners down low that just pries out like a stake.
Once you have got these out, you must push up on the whole door panel as it has clips which are part of the door and grab when you push the panel down.
Beyond that, 4 screws in the speaker (6 X 8).
Now it may be a little different on your year, but the same basic principle should apply.
Hope this helps! :laughlitt
1994 Mustang GT 5.0 Convertible
K&N Replacement Filter Element