If you are referring to how to enter the Form 1098 information, here are the steps:
In TurboTax online,
Sign in to your account, select Pick up where you left off
At the right upper corner, in the search box, type in "1098" and Enter
Select Jump to 1098
Follow prompts
You receive a Form 1098 if you paid any mortgage interest, mortgage insurance premium or points. Note that your mortgage interest might not change your total tax refund. It will only change if your total itemized deductions including the mortgage interest exceeds your standard deduction. In the TurboTax program, when you enter itemized deductions such as mortgage interest, property taxes, medical expenses, charitable contributions, the program will do the math to confirm if you qualify for the tax break. Unless the total of itemized deductions exceeds the standard deduction for your filing status, you would not see any change in tax due or refund.