You need to get the assistance of an attorney to set up the business properly. When you don't even know the proper starting point, you are not likely to be able to complete this without some assistance--and there are severe consequences for a business that purports to be non-profit and then hasn't complied with the proper filings. An attorney that specializes in establishing businesses, business plans and corporations can make sure that, not only will your initial filings be complete and accurate, but your yearly requirements will also be correct.
Providing users with information is not intended to create an attorney/client relationship. However, if in reading my response, you are interested in retaining me to represent you, please do not hesitate to contact me.
Corporations fall under the jurisdiction of the Secretary of the Commonwealth.
However, a non-profit has very specific criteria for filings and accounting. If those are not observed, it may have contact with the Attorney General.
Better to retain an attorney versed in non-profits and have him/her set up the association. Contact the MA and Norfolk County bar associations for referrals.
The foregoing is for general information purposes and does not establish an attorney-client relationship.