They cannot be done online. Online is only for current tax year. And those returns would then need to be prepared, printed and mailed. You cannot e-file a prior year return.
The other option would be to download the Forms and Instructions free from the IRS web site at this link
https://www.irs.gov/forms-pubs complete and mail to them.
NOTE: You will need to mail each one to the IRS in a separate envelope to be sure that each one is recognized as a separate tax return. And it's best to use certified mail/tracking service so that you know when the government receives them.
How do I file a prior year tax return?
