http://www.ehow.com/how_4512368_change-spark-plugs-car.html try this link :)How do you change the spark plugs on a 1998 ford expedition?
Take them out and put in the new ones. Not that hard to do. Just remember which order the plug wires go in.
What I do is remove and replace one plug at a time so that I don't have to worry about connecting the plug wires in the wrong order.
