Complex sentence: He sold his interest in the agency in 1933 and began publishing "Happy Days", a paper written for members of the Civilian Conservation Corps; his first order was for 400 copies and the first advertiser was GEICO.
Split into simpler sentences: He sold his interest in the agency in 1933 and began publishing "Happy Days", a paper written for members of the Civilian Conservation Corps. His first order was for 400 copies and the first advertiser was GEICO.