How do I add a 1099 form from 2017? I never filed it last year.

You can not add a Form 1099 from 2017 into your 2018 tax return.  You will have to file a tax return for 2017 to report your Form 1099 from 2017.  You can use TurboTax 2017 to prepare your 2017 tax return and then import your 2017 date into your 2018 tax return.