After answering that you don't have a 1098-T to enter, you will be asked if you qualify for an exception for not having a 1098-T. Answer yes to continue to the screens to enter expenses.
That said, why do you not have a 1098-T and how was your tuition paid? Depending on your answers, you may still qualify to claim tuition paid for the education credit. If you are or can be claimed as someone's dependent (e.g. your parents), you do not qualify for a tuition credit or deduction and TurboTax will not let you enter expenses.