Your contributions to the Thrift Savings Plan are reported on your W2, Box 12, usually with code "D" or "E." Box 1 of your W2 should be reduced by the amount of your contribution (unless it's a Roth 401k). No additional reporting is necessary.
For withdrawals from the TSP, you should have received a 1099-R, which is entered here:
Click Federal Taxes (top menu)
Click Wages & Income (just below top menu)
Scroll down to Retirement Plans and Social Security and click Show More (if necessary)
Click Start next to IRA, 401(k), Pension Plan Withdrawals (1099-R)
Enter your 1099-R exactly as printed, paying special attention the the distribution code in Box 7 and the "IRA/SEP/SIMPLE" box.
