Contributions to your TSP are reported with either code D or code AA in box 12 of your W-2.  Enter these only in box 12 of TurboTax's W-2 form.  Your employer has already excluded these amounts from your taxable income shown in box 1 of your W-2 so you don't get to deduct these again.

Enter your personal IRA contributions under Deductions & Credits -> Retirement and Investments -> Traditional and Roth IRA Contributions, then answer the follow-up questions.