Third Brake light out, how to replace?

I know this is usually a simple thing to do but I can't fingure out the trick to removing the housing and to replace one of the 2 bulbs that went out on the third brake light of my 98 continental. Any tips? Thanks.

It's not in your owners manual (https://www.fleet.ford.com/maintenance/owners_manuals/results.asp).. only the bulb type :(

Ok, I found it...
The assembly needs to be accessed from the underside, in the trunk.

Open this PDF (http://www.keepandshare.com/doc/view.php?id=597395&da=y) (from your 1998 FSM, available on my web page) for the instruction.

Perfect, thank you very much Towncar!