In order to file taxes from the past, you will need to purchase and download the software for those particular years in order to complete Tax Returns for those years. These returns will need to be mailed in as only the current year can be E-filed through TurboTax.
Here is a link to previous years product options: TurboTax Previous Years Products.
Check out the TurboTax FAQ below for more details: https://ttlc.intuit.com/replies/3301770