What do I need ?

• an editor for plaintext:
  emacs, vim, metapad (Windows)
• or (optionally) a L^ATEX environment:
  TEXnicCenter (Windows), aucTEX for emacs
• a L^ATEXdistribution:
  teTEX, mikTEX (Windows)
• a graphic program to create PostScript or PNG images:
  xfig, the imagemagick suite