sassycat - my experience and advice mirrors moptop's - show him how BDSM can be part of something he likes (oh, BJs for example...give them on your knees and ask for whatever level of force/hair/head manipulation you'd like and he might be willing to do). That was where I started finding what it felt like to me to be submissive, and then began sharing my feelings and desires with him - and we have progressed at a slow, steady pace since. Now, 10 months later, he's become a loving Dominant, curious and excited to see where we go on this path next. (And wanting to be the guide on that path, rather than me. Yes!!)
Good luck to you - I hope you find what you are seeking.