a basic car, you would remove the panel that has the window/door lock controls, and unplug the harness (given that you have power windows if you have manual windows, then you need to remove the crank),the panel probably has a screw that is accessable with that panel out. pull out the inner door handle (probably a small pocket in your case) there will probably be another screw there too. the panel should have a few plastic clips probably four or so, take a tool that looks like a screwdriver with a fork at the end and lightly pry the clips out. then check the perimeter of the door for screws/clips and pull the door panel straight up, it sits on either one or two hooks.
if there are any other components in the way, such as the stock tweeter locations i have in my cobra, then those need special attention as well. when you get the door panel off hang on to it and unplug any other harnesses or wires that are there.