I need to prepare and file for 2015 as well as 2016. I want to start with 2015.

[jeannecb]

I want have a much better understanding of my taxes and to file myself.  I have resources but get anxious and stupid about taxes - just collect paper and give to a nice advisor.  I want to be able to do this myself.

[jerry2000 · Accepted solution]

Turbotax Online works only for current year (2016) taxes, and not for any other year.
If you want to use TurboTax for any other year you will need to purchase the Desktop Version for each year that you need to file. You can do that at this link:
http://shop.turbotax.intuit.com/personal-taxes/past-years-products.jsp

You can download the Forms and Instructions free from the IRS web site at this link:
http://www.irs.gov/app/picklist/list/priorFormPublication.html

In any event, you have to file the return by mail. Turbotax does not support e-file of prior year returns. Tip: If you prepare multiple years of prior returns, mail each one to the IRS in a separate envelope to be sure that each one is recognized as a separate tax return.