In order to e-file your State tax return your federal return must be e-filed and accepted first and your state must have finalized all its forms.
Once your federal return is accepted and your state forms are available (check the state forms availability table at the bottom of this answer), you can return to the program to file your state return. Instructions to return to file your state are in the FAQ below. Select the blue drop down for Online instructions:
https://ttlc.intuit.com/replies/5269973
State forms availability table:
https://ttlc.intuit.com/replies/3319879
