There are several types of FSAs (Flexible Spending Arrangement) that the IRS recognizes: a general purpose health FSA, a limited purpose health FSA, and a dependent care FSA.
For both the general purpose health FSA and a limited purpose health FSA, there are no reporting requirements on your tax return. That is, there is nothing on your W-2 that even refers to these FSAs, nor anything else you need to enter into TurboTax.
For a dependent care FSA, there is often (not always) an entry in box 10 on your W-2 showing the amount of your income diverted to your dependent care FSA. This is automatically entered when you enter or upload your W-2.
However, this alone is not sufficient to complete your dependent care information. You must also proceed to the Child and Dependent Care interview and answer the questions there. You can get to this interview directly by doing a Search (upper right) for child and dependent care and clicking on the jump-to result. Mac users will look for child and dependent care in the Topic List.