I suggest you contact the building department, and asked for the C/O department they will be able to help you.
Also, You should interview some Real Estate agent to assist you in selling your house.
It depends on what year your home was built. Some homes in Staten Island were built prior to the city issuing C of O's. If you did need to obtain one depending on the work outstanding in the dept. of buildings, you may need an architect or just an expeditor to file the paperwork. If you you would like me to research it for you all I need is an address and I can point you inthe right direction.
A C of O is necessary when you sell a home in Staten Island. The purchasers' attorney will require it. You could check online at NYC building department and I suggest you discuss the situation with your attorney. Best of Luck!