no such thing as dumb questions!
so the way it works varies on position preference but, as you can see in the picture, the rope's quite long, which might give the wrong impression here. i just bought extra rope to be sure i'do have plenty to work with, if i needed for some reason but, for this setup i wont be using all of it.
i'll set up the slip knot around my neck, tilting my head back by looking upwards, then i'll position the knot just under the adams apple, and squeeze in the knot with my hands as tight as i can first (without blocking my airway), and finally, slowly bending my knees and leaning foward, leting gravity do the rest.
now... as to the position where one places the knot around the neck, if its right under the jaw line, or abit lower etc, this changes on personal preference, and acording to how the person managed to achieve carotid compression more easly. it varies from person to person, the only way to figure it out is by doing some testing but, it can get tricky and especially very risky so, please be very careful with it, as you might just CTB by accident/before you meant to.
i'do suggest taking some time to research this further, as you can find lots of partial hanging guides under the sticky threads or by using the search function.