If I only have a 1040 form can I file my taxes?

An IRS Form 1040 is the U.S. Individual Income Tax Return you send to the IRS - https://www.irs.gov/pub/irs-pdf/f1040.pdf

What exactly is your question?

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

Click on Tax Tools on the left side of the screen. Click on Tools. Click on View Tax Summary. Click on Preview my 1040 on the left side of the screen.