Would someone explain how to use those little bullets?

The bolt should close on a "go" guage. You should not be able to fully close the bolt on the "no-go".  If both hold true then your headspace if ok.

Quick and Dirty...

Top cover removed, recoil spring removed, pull carrier and bolt back, stopping just in front of the ejector.  Insert the gauge under the extractor and "slowly" push the bolt and carrier forward until resistance is felt (DO NOT FORCE).  Then read below...

Before doing any work to correct headspace be advised that not all AK type rifles will close on a "Go" gauge.

I have checked many rifles from "Home Builds" to "Factory Builds" and some will or won't close on a "Go" gauge.

In light of this I use the following methods...

#1 - If the bolt "WON"T" close on a "Go" gauge, I then check it with a factory cartridge. If the bolt closes on the factory cartridge, I consider the headspace to be good. If the bolt "WON'T" close on the factory cartridge, you have insufficient headspace and additional work will be needed to correct this.

#2 - If the bolt "WILL" close on a "Go" gauge, I then proceed to the "No-Go" gauge. If the bolt "WON'T" close on the "No-Go" gauge, I consider the headspace to be good. If the bolt closes on the "No-Go" gauge, you can then proceed to check it with the "Field" gauge. However, for me the "No-Go" gauge is the limit for me, if it closes on that gauge, I'll get another barrel.

Still better yet:

http://www.gunco.net/forums/showthread.php?t=2557

even has pictures

You need to be a gunco member to see the PDF, not a biggie just sign up!

www.gunco.net/forums/showthread.php?t=2557

Made it HOT for you.