What did you pay for? Did you pay last year for 2018 online version? Or did you buy the Desktop program?
You can't efile a prior year return. You have to print and mail it.
If you used the Online version. How to finish a return you started online
https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-finish-a-prior-year-return-that-i-...
