You should have received a 1099-R from the IRA administrator. To enter it:
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.
Be sure to answer the interview questions related to "What you did with the money."