to take the plug out, put a spark-plug wrench on it and loosen it up. Then unscrew it out of the top of the head. When putting it back in, be careful to start the plug threads by hand so you don't mess up the threads. Once you've got it started, tighten it by hand and then snug it up with the plug wrench. Don't over tighten or you risk breaking the plug.
As for the gap, buy a gap tester from nearest your autoparts supplier. Find out what the gap is supposed to be for the BRE8S blaster plug and measure the gap. If the gap is too tight, then use the gap tester to open it up a little more. If the gap is too big, again use the gap tester to close the gap a little.
Hopefully I answered your question and this all makes sense.
