Hello and thank you for using just answer.
The spark plugs on your engine are rated at 120,000 miles between replacement. The vehicle requires iridium spark plugs (BE SURE TO USE THE CORRECT PLUGS!)
To service the plugs you need to remove the black plastic cover on the top of the engine, you will see 2 10mm crown nuts(black in color) toward the front-remove these and pull straight up on the cover to remove.
Once the cover is off this exposes the 4 ignition coils that cover the spark plugs, remove the 10mm bolt (silver in color) that holds each coil down to the engine, unplug the electrical connector from each coil and then using a sparrk plug socket and a extension of at least 6 inches replace each plug and reassemble.