OK i did mine 2 weeks ago so I know the process......
-Once you have removed the NISSAN cover, undo the electrical plugs (one for each spark plug)
-Take off the plug (just pulls off)
-The you will be looking at the top of the spark plug.
-In your socket set you will have a really big socket (i forget the size) and use the extension arm, put this socket over the spark plug and undo.
- Be careful not to drop anything into the whole (do 1 plug at a time to avoid dropiing anything down there)
- Get the new spark plug, screw it in (VERY TIGHT)
- Put the plug back on
- Continue.
:D hope that helps