Complex sentence: Starting out as a blog written by the two teens, but has grown into a nation-wide movement, with a September 15,2007 conference in Indianapolis, Indiana drawing over 1,8000 young people.
Split into simpler sentences: Starting out as a blog written by the two teens, but has grown into a nation-wide movement. The most recent, a September 15,2007 conference in Indianapolis, Indiana drew over 1,8000 young people.