First of all, don't just unscrew the 2 Phillips head screws from the outside. It goes against common sense but if you do ( which you probably already did which would be why your here ) you will hear plink plink rattle rattle. That would be the 2 nuts inside dropping to the bottom of the inside of the mirror.
You need to do this job from the inside. Yes it's easy but still a pain in the backside. You'll need to remove the backside of the mirror cover to have access to the 2 screws on the market light. You need to remove both mirrors. It's the same process for the main and spot mirrors. First center the mirror then tilt it down all the way either by pushing it with your hand or by remote. Then push/pull the mirror up releasing it from holder just as if your replacing it. Be careful not to yank the wires for the mirror heat. Unplug the 2 wires for the mirror heat and the mirror is free. It's the same for the spot mirror. Remove 6 torx screws and the CB antenna and the chrome back of the mirror will come right off. Turn the rubber light holder thingy about a 1/4 turn and pull it out. NO NEED TO REMOVE THE 2 SCREWS HOLDING THE MARKER LIGHT COVER ! Just replace the bulb and reverse the process.