How can I file for my 2017 return ? Essentially, I filed when one should have...but didn't finish the process by mailing it in as requested due to it being only $18. Well, now I need my 2017 return fo

https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-finish-a-prior-year-return-that-i-started-in-turbotax-online/00/26322

You did not finish your question.  You had more space to use below the subject line, but you did not use it or for some reason your question was cut off in mid-question.

If you did not either e-file or mail in your 2017 tax return, it was not "filed" at all-- but it was "prepared."  At this point you cannot e-file a 2017 return.  You must print, sign and mail it to file it.  If you need to make any changes at all to it before you print it, then you need to use desktop software to make those changes. 

To finish a prior year return started in TT online:https://ttlc.intuit.com/questions/2559403-how-do-i-finish-a-prior-year-return-that-i-started-in-turb

When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s.  Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS and/or your state received the return.