How to find the button "Transmit my Returns now ?

This is my 3rd time using Turbo Tax, although I think that I sent the E-file apparently I did not because I never got a confirmation that it was accepted. As I did not get any answer I sent the balance due by certified mail on April 10 and I was confirmed the received payment on April 14. Today, still thinking that I sent the E-file, I tried to get the status directly on the IRS site. Due to I could not get any information I addressed the question to Turbo Fax and the system let me know to connect to  "E-file status lookup tool". I did,  but the answer of the system was No Record Found. Then, I follow the simple solution proposed by the system "Open your return and go through the File section again. Make sure you select the Transmit my returns now button". but I do not know how to reach it.  What do I have to do?