How do i remove and replace the driver's side mirror?

If the metal pivot arm is not broken you can just replace the glass and plastic housing. To remove the glass you tilt the glass down towards the floor and use a wide plastic or wood bladed object to prise from behind, the glass should pop off from its clips. Remember to catch it if its not damaged. To remove the housing once the glass is out you need to look underneath the mirror unit, there you will find a small plastic bung, gently prise it out and then use a long small flat bladed screwdriver straight up inside the hole and lever towards the front of the car whilst lifting straight up on the plastic housing, this should then lift off. To replace just slot the new housing on and click into place then fit the glass back, remember to connect the wires first if it is a heated glass.
If the metal pivot arm is broken then you will find the remaining screws behind the plastic trim inside the vehicle.

You will have to remove the entire door panel to be able to get to the mirror bracket.