Where do i enter HELOC interest paid?

In the section for the 1098 under Your Home

To get there select 

1. deductions and credits
2. Your Home
3. 1098 Mortgage Interest

The interest from your HELOC is only deductible for the amount that was used to buy, build or substantially improve your home.  If this HELOC was used to refinance other debt, make a major purchase like a car or boat, the interest on that portion is not deductible.

 As you walk through the questions in TurboTax, you will be asked what you did with this refinance.  You can have TurboTax help you determine the amount that is deductible. You will need to know this for the life of the loan.