Complex sentence: Series creator Eric Kripke had previously written for the WB series "Tarzan", and was offered the chance to pitch show ideas to the network; he used the opportunity for "Supernatural", a concept he had been developing for nearly ten years.
Split into simpler sentences: Series creator Eric Kripke had previously written for the WB series "Tarzan", and was offered the chance to pitch show ideas to the network. He used the opportunity for "Supernatural", a concept he had been developing for nearly ten years.