nowhere really. Turbotax no longer supports those years. you can find offers for them on the web but they can not be updated and no state returns are available. if you open your .tax#### with them you could easily change the return from what was filed.
However, there is a website we do not vouch for that you can e-mail the .tax#### files to and for a fee you'll get a print out
https://www.taxprinter.com/
you can file form 4506-T with the IRS to get transcripts - free
or 4506 to get copies $43/per year- time may be running out for 2015
https://www.irs.gov/pub/irs-pdf/f4506.pdf
https://www.irs.gov/pub/irs-pdf/f4506t.pdf
