well
ive got a 2002 pontiac grand am.. same aspect
first pull your rear seats down, in my car.. in my trunk.. up top on the inside there are two peices of a rope like stuff, pull those and it will release them then push/pull them down
second, you will see about 3-4 plastic screw looking things, their look screws with plastic threads.. just pull those out
then pull out the plastic peice that was behind held on by those
then you pull out the actual rear deck it's self.. this is VERY hard to place back in just so you know. its the very back part of your car... make sure you pull each side at a time you cant pull it all out at once pull the left or ride side about 60-80% out of the way before trying to remove the other side, this is a pain in the ass to put back in and out
then you will see the stock 6x9s there will be little clips holding them in place, remove the stock speakers.. there will be the adapter that you need holding them in place.. it might look like the whole speaker but its not apart of it this is HARD to remove the speakers from this thing without braking one of the legs holding the speaker in, take a butter knife and slide it on the side of one of the hooks holding the speaker to the mount and apply pressure to get it out and then you can fit the after market speaker in the stock speaker mount
also make sure you have a rear speaker wire harness for those, you can get a pair at best buy for 11.99. you should get a set of these
also, make sure those speakers actually fit because the rear deck can squish the tweeters on top of the speakers when placed back in the car, i ruined a pair of 200$ polks because the measurements werent correct