If you're trying to open the PDF file, then you'll need a PDF reader on your computer in order to open the file. If you don't have a PDF reader, you can get a copy of Adobe Acrobat reader for free here.
If you filed the 2016 return using the TurboTax Desktop software and you're trying to open the .tax2016 file then you'll need to install the 2016 program on the new computer before you can open that file. If you have the 2017 desktop software you can open that file to transfer your 2016 data to your 2017 return to start your 2017 taxes.
