Turn of lights?

Is it true that by turning of your lights will really help global warming? isn't the true cause from polution & such? which is making the ozone layer thicker or something .. Ever since i saw the Al Gore Movie i've been really concirened about it .. and yeah . So my question basically is How does turning of your lights help global warming? .. Global warming is basically the planet getting hotter right .. its just kind of not clicking for me?