Sources of light range from the physical (example, a tinderbox and lantern) to the ethereal. Be forewarned, the bearing light will declare your presence amongst others, should you have reasons to remain in shadow.
Light is sometimes an important commodity, especially when one is wandering around the land during the night or underground where there is no natural source of illumination. Most elect to carry lanterns or use charms and magic to conjur light sources for themselves. If you are without a light source yourself, take yourself to a general store or appropriate market stall and seek out a lamp; then fill it with oil and light it. You may find you need a tinderbox to spark the oil to life. Once lit, the lamp will burn brightly and illuminate your surroundings. Be careful if you are attempting to wander around invisible or in stealth since it is possible to give one's position away by carrying a light-source where none should otherwise exist!