how go you change the spark plugs

You will want to get a Haynes manual, That is a start. If you are not to sure on the procedure you might want to take in and get the plugs done, If you pull to hard on the wires or break a plug (they are made out of ceramic and are delicate), you will be in a rough spot. But if you are going to do them yourself get the manual and (watch the nuckles), carefully "pull/remove" spark pulg wire, losen spark plug, Gap new spark plug, install new plug (becarefull not to hit the new plug), DO NOT OVER TIGHTEN!!! you will strip the threads if you do.Do this ONE at a time. If you need to move anything to get at the plugs, remember where it was (very important). Depending on the mileage you might want to change the wires too. This is a somewhat easy job (but I have many years turning wrenches), some of these newer cars are a pain in the butt, and if something is moved or "disturbed", I find that the car might not preform as before, then you will need to find out what the issue is. I dont want to scare you, but if you are not sure I would take it in. Most shops around me only charge $120 (for a V-8) for a "tune-up" (change plugs, inspect wires and a few other things). In my eyes it is a good price and it will save you some aggravation if you are not to sure on the steps, Best of luck, hopes this helps, Cheers