Your FSA contributions are in box 10 of your W-2.
In the Child and Dependent Care Credit interview (Federal Taxes->Deductions & Credits->You and Your Family and click on "Child and Dependent Care Credit"), enter the total amount of your expenses. If the FSA part was correctly identified on the W-2, then TurboTax will be aware of it and will subtract the FSA amount from the total expense before computing the credit on the remaining amount.
