I receive a prompt to review my 1040. How can I access that part of the turbo tax preparation?

A 1040 is the tax return form you prepare here to send to the IRS.   If you start entering data in this software you are preparing a Form 1040.   Please look at it so you will know what you are sending to the IRS:

PREVIEW 1040

https://ttlc.intuit.com/questions/1901539-how-do-i-preview-my-turbotax-online-return-before-filing

Form 1040 is the main form for US taxpayers, so that is a very broad prompt. To do a general review of your tax return:

1. Open your return and select Federal on the left side menu.
2. Select Review.
3. Scroll down and click Check my return.
4. Click Continue.
5. If you get a screen that says, Let’s take care of these details now, click Review to the right of the first item on the list. 
6. Make any needed corrections. 
7. Repeat until you get the Ready to File screen. 

If this is not what you need, please respond back with more details of what you are trying to do.