Contributions to your employer provided tax deferred retirement account 401(k) are entered on your W-2 in box 12 with a code of D. They are not entered anywhere else on your tax return.
Based on your Adjusted Gross Income and your filing status you may be eligible for the Credit for Qualified Retirement Savings Contributions (Saver's Credit). If you are eligible you cannot use the Free online edition since the Free edition does not support this credit. You would have to upgrade to the Deluxe online edition for the credit.
