how to change spark plugs?

You need a spark plug socket (i.e. a special socket with a rubber insert which won't damage the ceramic insulator on the spark plug and which also grips the plug so you can withdraw it from the deep hole in the cylinder head in which it is located). You also need a torque wrench to correctly tighten the new plug when you have screwed it in (25 Nm is the correct torque). It goes without saying that you need an extension bar and socket wrench with the spark plug socket. You need a feeler gauge to check the spark plug gap which is 1.0 to 1.1 mm according to the Nissan Micra owners manual (but 0.9mm in the Haynes manual!)
BKR 5E-11 are the correct NGK plugs. Fitting plugs other than those recommended by the vehicle manufacturer may be false economy.

JD
January 2009