If god created earth who created him and so on and so on?

i mean the earth couldn'y just start out as nothing im mean theres just blank actully there wouldnt even be blank how did the world start out? it seems impossible how did people write records,how did scientist read them,how did cavemen reproduce if they were dim witted and didn't know about ual reproduction im in the 6th grade and i donm't understand and put it in a form i can understand