The tricky part will be the door handle cable. You need to unscrew 2 screws only, one by the door handle covered by a plastic cover and the other by the handle you pull and push to close the door covered by a plastic cap. You can then pull on the door panel towards you all the way around held by like 6 clips, so you will need to pull a bit hard. After that, you slide the door panel up and pull the panel not all the way out yet because its still holding by the cable from the handle. You will need to unclip that blue plastic clip holding it and swing the cable around a bit to unhook it. The cable is like a bicycle brake cable.
If you have rear speakers, it should be holding by one screw. If you don't have any, you will need to get some brackets back in the there because the speakers I bought, the brackets weren't big enough to fit in there. If you got the Sonic LS 4 speaker system, the speaker wires only run up into the body behind the seat belts. The speaker wires are not in the rear door so you will need to add some. The best bracket to use for the rear speakers are the ones that came with them, just rip out the old ones and use the existing speaker mount for your new ones. Or since I did not have rear speakers, I took them out from a 05 Impala in a local scrap yard that use the same speaker mounts.
Here is someone's speaker build that has pics of what I'm talking about;
http://www.sonicownersforum.com/forum/interior-ice-discussion/6931-my-stereo-build-bit-modest.html
And if you don't have rear speakers here you go;
http://www.sonicownersforum.com/forum/interior-ice-discussion/6948-no-back-speakers-base-model-4.html