Make sure you need to amend before you file an amendment. Social security is not taxable in MA so TurboTax would have subtracted any SS payments reported on your federal return from your MA return. But if you do need to file an amendment, there is a link with instructions below.
Did you file it with TurboTax Online? If so, all you need to do is log into your account and start an amendment. How do I amend my state tax return?