The tax withholding they took out? Have you got the 1099R yet? It should be in box 4.
You didn't actually pay the tax or 10% penalty (you pay a 10% early withdrawal penalty if you are under 59 ½). You had taxes withheld like from your paycheck. You still have to enter the whole gross original amount (before taxes were withheld) with your other income to figure out the total tax (and it may put you into a higher tax bracket) and then the withholding is subtracted from the total tax to figure your refund or tax due. The gross amount shows up,on 1040 line 4a or 5a and the taxable amount on 4b or 5b. The withholding will show up on 1040 line 25b.
You will get a 1099R that you have to enter into your tax return. They are usually issued in late January to early February. They might mail it to you or you might need to go to their web site to get it. The 1099R will show the tax you had withheld.
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.