Well you will need a copy of last year's return. You need to have the AGI from 2015 to efile. Go to H&R Block and try to get a copy.
If you can't find your return, request a free transcript of your federal return from the IRS.
http://www.irs.gov/Individuals/Get-Transcript
Or order an exact copy of your tax return (including all attachments) from the IRS. There is a $50 fee per tax return. See
http://www.irs.gov/taxtopics/tc156.html