A very useful Instructable by Captain MacTavish but I think I would stick with the method suggested here: http://www.theultralighthiker.com/if-you-could-only-carry-two-things-in-the-bush-what-would-they-be/ & here: http://www.theultralighthiker.com/how-to-light-a-fire-in-the-wet/
What you will need is a gum wrapper and a “AA” or a “AAA” battery
Step 1: Prepping
Place the negative part of the battery on the metallic part of the wrapper.
Step 2: The Fire:
Cover the top part of the battery and hold it there with something other than your hand! You will burn yourself, The FIRE!
Handy hint: ‘If you have no gum just get some steel wool [pot scrubber] and put some tinder on top of it,then get a 9 volt battery and touch on the steel wool and”hey presto” you have a fire!!’
See also How To Make a Fire with AA Battery and Gum: https://www.youtube.com/watch?v=-63ZsOEzsVg