remove the dome light and you can then get to the nut that holds the base on. From there is pretty pretty self explanatory.
I dont know what the ford part number, but if you search ebay you should be able to find one for around $10-15 bucks.
ZETEC Crew #26 SR #20 YELLOW BLAZE OWNERS GROUP#4
Moderator Pilot, 12 SE HB ╠╬╝, 2011 Ford Edge SEL AWD