You can prepare your 2015 and 2016 tax returns using TurboTax software and then NetFile them to CRA.

For 2016 you can choose to use our Online version or Download. For 2015, you will need to download and install the software in your computer. 

Links to the versions you need can be found here: https://turbotax.intuit.ca/tax-software/prior-year-taxes.jsp#2017

https://turbotax.community.intuit.ca/replies/2860808

You can also access forms from CRA to fill out and mail in to your Tax Services Office by following this link: https://www.canada.ca/en/revenue-agency/services/forms-publications/tax-packages-years.html