How do I get on the page to put the correct AGI?

Toward the end of your return, it will have you enter last years, AGI so that the IRS knows it's you and only you. 

Here are the steps you will need to follow:

To revisit the 2016 (adjusted gross income) AGI section in TurboTax Online:

1. Sign in to your TurboTax Online return.
2. Select File and you’ll get to the [Your name], just (…) more steps to complete screen.
3. Complete Step 1 and 2 if you haven’t already done so, then go to Step 3.
4. When getting to the Let’s get ready to e-file screen after selecting Step 3, select I want to e-file before you continue.
5. Follow the online instructions. When prompted, put in your exact 2016 AGI.
6. Continue through the screens until you’ve re-transmitted your return.