Complex sentence: Siriano debuted the spring collection for his first line, Christian V. Siriano, at New York Fashion Week on September 11th, 2008, sponsored by Cibu International Haircare Products, which is Bubbles Salons product line where he started his costuming career.
Split into simpler sentences: Siriano debuted the spring collection for his first line, Christian V. Siriano, at New York Fashion Week on September 11th, 2008. His show was sponsored by Cibu International Haircare, the product line of Bubbles Salon, where he started his costuming career.