Remove the screws on the door panel; there are six, two on each end of the
panel, one in the "pocket" of the door handle and one behind the latch that
opens the door.
Pop the clips at the bottom of the door and the door panel will lift off.
Once free, you need to remove the plug the goes to the window/lock controls
and your done.
You will now see the speaker, which is screwed to a plastic adapter and very
easily removed.
What fits? Crutchfield always has a handy matrix for that (they're pricey
and I never buy from them but the matrix is cool.)
http://www.crutchfield.com/S-kqPoPnH9Hs8/cgi-bin/prodgroup.asp?g=400&l=C
They list 52 items and any one will outperform the factory crap.

To learn more, there are some groups you can lurk in:
www.dsmtalk.com  inside you'll find an audio sub-forum that is specific to
our cars.

www.bcae1.com/  a huge casche of audio info.

http://www.carsound.com/forum/   GREAT reading here!

Now, as to what killed your door speakers......Door speakers are at best a
"Mid-Bass" speaker and at high power levels, can't deal with a full-range
signal. Powerful bass will tear them up. Door speakers need a crossover to
filter out bass and send only the part of the signal the speaker can
reproduce.
This will help explain: http://www.bcae1.com/passxovr.htm

I am running these
http://www.qlogic.ws/2003/products/qforms_detail.jsp?classID=57&productID=5694
stuffed with BostonPRO 6.53 three-way speakers.
6 1/2 in the door, a 5 1/4 and tweeter in the Q-form panel, with a single
12" dual voice coil sub in the rear. (no 6x9's or any rear fill at all)
The sound is good. It plays VERY loud with low distortion.

good luck