cristinasmile,
I would encourage you to read through a lot of threads and learn a little more about greek letter organizations. It would help you out a lot in your journey. There are only 26 npc groups. You could have checked to see if you had picked one of those on the website yourself. Really no need to contact NPC, although I am sure they were happy to help you out. They are really nice like that.
Local sororities are usually started for one of two purposes. One is to be truly local and never affiliate. The other is with the purpose of affiliating with a larger group in the future. Either way when you start your group you will chose your own name, letters, mascots, colors etc. You would want to have symbols that pertain to your group, and if you affiliate in the future that is when you would start using information from another group. I think I am not the only one who is still in the dark regarding your purpose. But I am always in favor of adding greek life to a new school! If you are striving to become an npc group in the future, keep your options open. All GLOs have different criteria for colonizing a local sorority. Your first choices might not be the right fit.
Check out this thread on naming your org, it might explain a lot to you.
Kappa Gamma Delta
Good luck! There is a lot of great information in these threads and lots of great people willing to offer great advice.