The side view mirror housing unit has become loose and rattles when the driver side door is shut. Everything is working, ie , mirror adjustments, mirror defrost. I assume that I need to take off the interior door panel to fix. How do I do this?

To remove a door paneling check the door handle and arm rest for screws or screw covers first.

Check the rest of the panel for screws, however most of the time they are plastic clips.
Once all the visible screws are removed from the panels try using a small screwdriver and pop the trim. You might need to use a bit of force, but be careful not to pull any wiring from the window switch (if equipped with power windows). let me know the exact vehicle and I will assist you with any other tips I have.

Thanks Tim. Sorry I didn't include the car information in the body of the question. I thought you'd be able to see it on my profile.
It's a 1996 Corvette. I assume that there will be wires and such that may need to be unplugged or something like that. Should I disconect anything or take fuses out so window doesn't accidently move? Thanks again for the info.