After you enter your IRA contributions in the Traditional IRA and Roth IRA input section of Deductions & Credits, you can continue through the interview questions. You will be asked if you made any nondeductible contributions to your IRA, say yes, and continue through the interview to input your basis.
I'm using the Mac desktop version of TurboTax and this question is not asked of me. Thus when it generates the form 8606, the prior year basis on line 2 is 0 which is incorrect. How do I get help to fix this if my product is not working?