what car is it?
if its a headlight adjustment problem, you can fix it yourself. if not and you thing one headlight is weaker than the other in terms of providing lighting, you may need an electricians help.
park your car approx 7 meters perpendicularly infront of a wall. using the low beam, check if the left and right headlights are aligned. this is what they should look like.
if the headlights are misaligned, this is what they will look like.
you are only checking for the headlight height adjustment, for which there are screws on top of the headlights. The side adjustment screws are mostly to the side of the headlights.