If you used money from a 401k before you reached age 59 1/2 you will owe the 10% early withdrawal penalty as well as ordinary income tax. You do not get an exception to an early withdrawal from a 401k for purchasing a house. The exception for that is only for a traditional IRA.
To enter your retirement income, Go to Federal> Wages and Income>Retirement Plans and Social Security>IRA 401 k) Pension Plan Withdrawals to enter your 1099R.