To remove the stock...
Take a standard screwdriver and pry up the little top vent where the defrost comes out of. It runs the length of the Jeep. There are 2 screws right under the defrost vents. and then remove your ashtray, theres a screw back there. Once youve removed the 3 screws, give the molding a good few tugs and itll pop out with some encouragement. unscrew the 2 bolts in the radio and pull it out. Unplug the radio antenna, and wiring harness. Youll need to buy another wiring harness that will fit the Jeeps existing one. Youll then soder/heatshrink the wires from the new harness to the apline harness.
If you can't take a nano-second to press shift/period/etc. and make proper sentences and paragraphs, I don't know if I can take a few minutes to respond to your topics... It doesn't have to be perfect by any means, but a little effort goes a long way.
I just swapped out my head unit in my 2004 Wrangler last week, so I may be able to give you a few pointers. I'm not exactly sure where the ash tray is located on older models, but it is not on the dash in the 2004's. It is actually just a round ash tray that is placed in what is basically another cupholder on the center console. You don't need to do anything with the ash tray (or the lack thereof) at all.
I'll try to recap some of omnipseudo's steps per the 2004 model:
1) Remove the long, skinny trim piece that is located near the windshield. It is almost as wide as the whole windshield. Just pull up on it and it should pop right out.
2) Remove the two screws that are located at the top of the bezel (surrounds the vents, radio and HVAC controls). You should be able to see these screws provided that you removed the trim piece in step 1. Carefully pull the bezel outwards and upwards and it should come out.
3) Remove your glove box by opening it and detaching the nylon string piece that holds it in place.
4) Reach through your glove box and behind the radio to remove the bolt (don't remember the size) that is located on the lower, right rear portion of the head unit. This step is by far the most difficult just because it's such a small/awkward space to reach your hand.
5) Detach the factory wiring and antenna from the rear of the radio.
If memory serves me correctly, that's about it. Good luck!