Complex sentence: Out of high school, she began working temporarily for her family's clothing business, and that led to a full time job as a fashion and advertising designer for the company, as well as co-running a copy center with design section.
Split into simpler sentences: Out of high school, she began working temporarily for her family's clothing business. The experience led to a full time job as a fashion and advertising designer for the company, as well as co-running a copy center with design section.