X I think it is great that you want to start an organization at your non Greek School!
Well, first you need a group of ladys the larger the better! Next once you are a viable organization, you need to get recognized by the school.
Once that far, you can petition a National Soroity, or more than one and have them send someone to talk to you. This gives both partys a chance to check each other over to see if there is a fit between you!
All i can say i have been there and it is a tuff road to plow but the rewards are well worth it in the long run/ the very bestest of luck!!!!!!