Making fire in the wild is not magic or a TV trick: it is basic chemistry applied with patience. You need three elements at once — heat, fuel, and oxygen — and a clear sequence: tinder that catches a spark, fine kindling that carries the flame, and progressively thicker fuel wood.
With a survival starter (ferrocerium rod or flint and steel), the spark is predictable if you aim at dry tinder: birch bark, fungus «punk» wood, dead plant fluff, or certain tree fibres. Avoid green moss or branches picked from wet ground; look for suspended material sheltered from wind and test it dry first. Scrape the ferro rod firmly close to the tinder; with flint, strike steel on stone and direct sparks into the same bundle.
Without modern tools you can use friction (bow drill, fire plough) or percussion with flint or other hard rock, but those demand prior practice and climate-appropriate materials. Do not confuse a video demo with real skill: save those methods for controlled training, not your first cold night out.
Build the flame on mineral ground or cleared earth, away from roots and low branches. Start with a tipi or log-cabin lay to let air flow; add fuel the thickness of a pencil, then a finger, and only then full logs. Respect local rules: in many parts of Spain seasonal open-fire bans apply; carrying a starter in your kit does not exempt you from fines or from starting a wildfire.
Always extinguish until ash is cold to the touch: water, soak, stir, repeat. Carry more water than you think you need. Fire warms, cooks, and lifts morale; mismanaged, it destroys the landscape you meant to live in.