Pull off a spark plug wire,, may have to twist and pull.Get yourself a spark plug socket from any auto / hardware / tool store and extension for ratchet and loosen out spark plug.Before you pull out plug you may want to blow plug area with air hose so as no dirt falls in hole.If you are doing all , do 1 at a time so you dont mix up wires.
I swear every time I change or even look at my spark plugs, I scrape my hands on something. Just a little annoyance, that'* all. Oh, and if you find the metal spark plug wire covers, discard them. They just make future changes more difficult