To build a campfire step by step: (1) Choose a safe location with a designated fire pit, away from branches and dry grass. (2) Assemble the floor using two parallel logs. (3) Add two more logs perpendicular on top (log cabin method). (4) Place tinder — dry paper, cardboard, or dry twigs — inside the structure. (5) Add kindling on top of the tinder. (6) Use a lighter or matches to light the tinder from the bottom. Keep a water jug nearby and never leave the fire unattended.