You will enter the 1099R on your tax return. Tax was withheld when you took money out of your 401k just like when your employer withholds for tax. The money you took out is taxable income so when ALL of your income is combined, the software will calculate your 2019 refund or tax due. If you were under 59 1/2, you are also subject to a 10% early withdrawal penalty for that withdrawal.
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.
If your 1099R has not come yet, it will arrive in late January/early February.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**