take a magnesium flint stick and a sharp knife. scrape shavings of the magnesium bar, you need at least enough to cover a quarter, then put flammable shavings on top of the magnesium shavings. (make sure you have dry wood/twigs to keep the flame going). next put the knife at a 90 degree angle with the blade touching the flint. make quick steady strokes aimed at the magnesium shavings and eventually it will catch fire.