Replace a driver side manual mirror on 2005 Ford F-150

I need to replace a driver side manual mirror on my 2005 F150. I have
the replacement which I bought at the dealer. It looks like I need to
pull off part of the door panel to get to the screws. Can you tell me
how to do that without screwing it up?

To
access the side mirror mounted nuts, yes, the door panel will need to
be removed. I've