The Writers' Circle

I'm a generally artsy person.  I do a lot of visual art and I used to do a lot of writing but I have been kind of lax lately.  I'm trying to find the inspiration to start a new book, possibly book series that I have been tossing around for about a year.  I have started creating the world, the characters, the religion, things like that, but I'm having the hardest time pounding out the beginning of the book.