Are you asking about contributions to a 529 plan or withdrawals from a 529 plan?
Either way, you usually don't enter it anywhere.
There is no federal deduction for making a contribution to a 529 plan. Some states allow a deduction on the state return. If your state is one, it will come up in the state interview; usually in the "Here's how (your state) handles income differently" section.
529 withdrawals (distributions) are reported on form 1099-Q. You can just not report the 1099-Q, at all, if your student-beneficiary has sufficient educational expenses, including room & board (even if he lives at home) to cover the distribution. When the box 1 amount on form 1099-Q is fully covered by expenses, TurboTax will enter nothing about the 1099-Q on the actual tax forms. But, it will prepare a 1099-Q worksheet for your records. You would still have to do the math to see if there were enough expenses left over for you to claim the tuition credit. You also cannot count expenses that were paid by tax free scholarships. You cannot double dip!
