You have three options
If you don't have media in your FTM 2011 file,simply make a GEDCOM and then open it in FTM3
OR
If you have media then you will have to download the File Migration Utility
http://help.ancestry.com/app/answers/detail/a_id/5313/kw/fil... and convert the file
OR
get someone to convert your file from 2011 with FTM 2014 and then do a File>Backup
The .FTMB file produced from FTM 2014 can be directly opened (restored) in FTM3
John D