Call the Beau of Vital Statistics in you state and request a form to have the Birth Certificate change. Then fill out the form and take it to a Notary and sign it and have the form notarized. You must pay a small fee for this service. Take care.
How Do I Change My Daughter's Father Name On Birth Certificate?
Go to your local court house and have it changed
Well darling you would need to take a paternity test to prove this and when it proves so you go to where she was registered and you ask them to change it for you. Sorry if I'm wrong but that is how they do it in my country