I'm employed but started home business w/roommate. I own home (roommate does not). How do we each report home business? Can I deduct portion of my mortgage/utilities?

What form do I use to report a startup home based business operated with another person that I am not married to? I own the home.  Can I deduct a portion of my mortgage / utilities that are used for home based business?  How do we each report the business expenses/income on TurboTax?