Hi. I am trying to file, but I get an error message saying duplicate, file emended through mail. How do I do that? I am very confused.

if you filed amended through mail why are you trying to file again.  

Thanks for your sarcastic comment, which absolutely helped in no way. The error message I received is telling me to file amended through mail. I have submitted electronically. I do not know why I am receiving this message or how to file amended through mail? Do I print a copy through turbo tax of my 2018 return or 2017?