The procedure to change it is probably in your owners manual under "Maintainence and care."
It's in my 1998 manual, and I change mine every 15K miles, which Ford recommends and from all the dirt in it, I wouldn't go past this mark.
'98 Taurus SE w/24V Duratec. w/100,000 miles
'87 Mustang LX 5.0 Hatchback w/227,000 miles
'05 Mazda Tribute s AWD w/85,000 miles
Original owner of these vehicles