How do I find out if my return was accepted?

Did you go all the way through the File tab, through the 3 steps and hit the big orange Transmit Returns Now button?

If you used the Online version you can check your efile status here     

https://turbotax.intuit.com/tax-tools/efile-status-lookup/   

When you efile you get back 2 emails.  The first email only confirms the transmission.  The second email says if the IRS (or state) Accepted or Rejected your efile.  And check your spam folder for them.

When you log into your account you should also see the status and if it was Accepted or Rejected, Started, Printed, Ready to Mail, etc.  What does it say?

@danseasdad when you efiled, you would have received an email stating so.  'accepted' is the same thing as the mailroom receiving a physical file.  

But are you really asking if it was processed? that could take awhile and you should check the IRS refund tool for status. 

https://www.irs.gov/refunds