How do I enter my 401k deduction I cant seem to get back to that page? ?

[MinhT]

You do not need to enter your 401(k) contributions separately in TurboTax.

Your 401(k) are already accounted for in your form W-2. They have been deducted from the amount of wages in box 1 of form W-2 and are excluded from taxation. They are also reported in box 12 with code D.