The final step is to click on the "Transmit my Return Now" button on the File screen. This screen happens after your identity is verified. Are you on the screen but just cannot see the button? How far into the filing process are you when you encounter difficulty?

what should i do?

You may to have go back to Federal review and check for errors and accuracy, or the return may have used a form that isn't avaialbe for e-filing yet  You can do a federal review to check for error/s by:

1. Click Federal Review located on the upper right hand side of the screen .
2. Click review to each details, if any.
3. You do the same on your state income tax. 
4. When done fixing, go back to Federal Review to check if the return is ready to e-file.