Ensure you have 2 sticks in your bags, a full Stamina and standing right next to the object you're going to light on fire. Press Adventure - Light Fire, you'll see a craft window. Press "Cratf". It takes a long time. When the craft completes, your cursor is turned into a firebrand. Right-click the object you're firing up. If the firebrand goes out before you manage to fire the object, repeat the process.