hey man i've done this in my 6th gen and my buddie's 5th gen. i really wish i made a writeup because i've helped many ppl do it since but i'll help u out aswell.
what u have to do is cut off the tops of those melted plastic things u see. i used a razor blade.
after you cut off all the melted parts you'll be able to remove the arm rest from the rest of the panel
pull off the old fabric
glue on the new fabric using 3m super90 or dap contact cement(better hold than 3m but not as easy to apply)
looking at the doorpanel you'll see hollow plastic cylinder which u cut the melted part off of before.
use a small pilot drill bit to clean out the hollow part of the cylinder(some of mine had a lot of plastic in the holes)
use a running tape then a bottoming tap to thread the inside of each cylinder
now get some very short bolts and washers and reattach the armrest to the door panel with the bolts(use the washers where the cylinders are too short to have the bolt fully threaded)
if u need more help lemme know
Luke
ps: here's mine