There's a hole in the bottom of the mirror shell and I believe its a Phillips head, you undo it and the mirror comes out and the bulb socket is there in the housing. I believe the bulb is a 7443. The picture isn't the greatest, it will give you an idea of the assembly.
Keep a hand on that mirror when removing the screw. BTW. When I removed one of the mirror screws on GORDO's 2010 Wing to install the wind deflectors, the Philip head screw was nearly seized. It was a pucker moment. Can't hurt to put a bit of anti-seize lock-tight on the threads. One doesn't remove these screws too often.