VERY VERY IMPORTANT HERE!!!!!!
Do ***not*** put pressure on the center electrode. You can not knowingly crack it and then have it break off in the engine.
You take the tool and a set of feeler guages to do this.
Just take out one of your old plugs and just play with setting the gap. Just apply small pressure on it then re-measure. If you over bend it.. it won't matter cause your throwing it away. Practice before doing your new ones. And please! If you've put pressure on the center electrode of a new one. Throw it away. This is the typical "newb" mistake. They set the gaps and then in short order thier engine is running rough. They wind up blaming the plugs for being "crap" when in reality they did'nt know what they were doing to begin with.
btw, I've seen people go most of thier life (younger guys) blaming one brand for being "crappy". It blows my mind how shallow people can be about one brand when they really ought to look in the mirror for the real "crap".
Having no experience, messing something up, and then blaming someone else is a HUGE pet pieve of mine. Quite the typical nature of young men too...