You need a tin of some sort it just hast to be a closeable tin that is kinda air tight like a tin of mints or maby a altoid can. When you get your tin you need to punch a small hole in the top with a small nail or 4-5 cm, but dont make it to big no bigger that 1cm . this must be done or you risk the chance that the gases presurize the tin and it will explode.
after that you are ready to char some cloth.
Step 2: Put the cloth in the can
Now you must gently put the cloth in the can after you cut the cloth in squares. you must not pack them in tight or by just throwing them in you should place them in gently like I did in the picture. Then put the cap on. also you must use 100% cotton for the cloth this is readlly avaliable by using a old tee shirt which I use and it works fine, but remember 100% cotton!
Step 3: Put it on the fire
now just start a fire not a blazing inferno just a calm fire or you can use the embers (lots of embers, this usaly works much better) set it some where in the fire where it will not fall over and watch it you will eventualy see smoke billowing out or it might start on fire. dont freak out just let it burn itself out and when there is no more smoke coming out take it out. what ever you do DONT! take the lid off right away just wait a little while for two reasons. one it is probaly really hot! and two if you open it before it cools, the oxygen will rush in and might start the whole thing on fire. then you run the risk of getting burnt and you will have to start over because the cloth is all burnt away.