To remove spark plug, open the hood. Then you will see 4 wired plugs in a row on top of the engine. These plugs have very small green, yellow, etc colored dots right under them (usually green dot on the far left plug). Each plug can be removed since they are connected w/ just one screw (typically on the top left side of each plug. Remove each plug at a time by removing the screw. The plug has a long nozzle connected to it. After removing a plug (w/ the nozzle), you will need any tool that can reach in the hole where the nozzle fits in. There you have to use a tool to loosen up the spark plug. Then use a tool w/ magnet on one end to draw in and pull out the spark plug. Then simply get another spark plug, drop it right in, tighten it (not too much, not too little), and then put back the correct plug(w/ nozzle) back on top of the spark plug. Tighten the screw.
To fix the 4th spark plug (far right), you have to unscrew and remove the air suction pipe by unscrewing it on several sections (usually 2 places, each having two screws). After 4th spark plug installed and plug put back on, put back the pipe, screw it and you're done.