The seat bottom has two clips holding it in place. Their is a plastic tab that sticks out that you push in to release them. The tab is located in the center of each side of the seat just under the front edge of the cushion. Just start in the center of each side of the seat and feel for it or look for it and get a flat head screw driver to push the plastic tab in and the seat will pop free. There is one on each side.
As for the side panel you have to remove the phillips head screw holding the clothes hanger from the top, then you have to remove the cover and torx style bolt holding the seat belt in place, there should be another plastic push tab near the seat belt mount that has to be removed, remove the two plastic tabs holding the rubber molding in the door jamb that attaches to the side panel. The upper panel then can be pulled out and there are tabs behind it that hold it in place that just pop out.
The big lower panel has 3-4 small tabs holding it in place that are located behind the back seat (so you have to put the back seat down to reach them). There is one more plastic tab along the top, towards the back of the panel, you also have to remove the door sill plastic. At this point the panel can be pulled forward (towards the front of the car) and maneuver it out. Just be careful as there are long alignment tabs behind the panel that can snap off. Not the end of the world if they do it's just one less thing holding the panel in place.