Installing a driver's side mirror, 1992 Accord

I am trying to install a driver's side mirror. How do I do it. I see there
is a black traingular piece on the inside. How do I remove it? Any help
will be appreciated

 

Someone asked the same question a couple of weeks ago. Do you have the
replacement mirror in hand. Is it remote controlled....is there an
electrical cable, about a foot long, with a plug on the end? To plug
the cable in you have to remove the upholstry from the door. With the
upholstry off, the triangular piece will be easy to remove.
I have had the upholstry off the door of a '92 Accord more than once,
it's not hard to remove or reinstall but I have not replaced the
mirrow, I worked on locks and windows.
Removing the triangular piece with the upholstry in place can result
in braking the tab off the triangular piece....I broke one.